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MATHEMATICS SUMMER REVIEW RESOURCE PACKET CONTENTS REVIEW SECTION 1 – ORDER OF OPERATIONS Vocabulary Numerical Expression: An expression, such as 6 + 5, that consists of numerals combined by operations and names a particular number, called the value of the expression. Algebraic Expression: An expression, such as 2x + 3, that consists of numerals and variables combined with operations. Each numerical expression should have a unique value. In order to avoid misunderstandings and errors, mathematicians have agreed on certain rules for computation called Order of Operations. (PEMDAS) Order of Operations P Represents grouping or inclusion symbols. The basic grouping symbols are parentheses ( ), brackets [ ], and the fraction bar. Expressions within grouping symbols should be treated as a single value and should be evaluated first. The fraction bar indicates that the numerator and the denominator should each be treated as a single value. When more than one grouping symbol is used, evaluate within the innermost grouping symbol first. E Represents exponents. Perform all operations with exponents. M D Multiplication and Division are considered to be on the same level of operational importance. Therefore, perform all multiplication and division in order from left to right. 1 A S Addition and Subtraction are also on the same level of operational importance. Perform all addition and subtraction in order from left to right. To simplify or evaluate a numerical expression means to apply the Order of Operations to replace a numerical expression by the simplest name of its value. Example 1: Evaluate 3 12 4 3 12 4 3 3 0 first Example 2: Evaluate 62 4 3 72 62 4 3 72 36 4 3 49 36 12 49 24 49 73 2 2 Example 3: Evaluate 3 2 5 7 2 3 2 5 7 3 7 7 3 49 7 147 7 21 To evaluate an algebraic expression means to replace each variable by a given value and then apply the Order of Operations to simplify the result. Example 4: Evaluate a2 2 if a 5 and b 3 a b3 a 2 2 52 2 25 2 23 a b 3 5 33 5 27 32 Example 5: Evaluate 2 2 8 a b 3b if a 5 and b 2 3 2 2 2 2 2 2 8 a b 3b 8 5 2 3 2 8 3 3 2 3 3 3 2 2 2 8 9 3 2 72 6 78 52 3 3 3 2 REVIEW SECTION 2 – OPERATIONS WITH FRACTIONS Multiplication Rule for Fractions: To multiply fractions, multiply numerators and multiply denominators. a c ac b d bd Example 1: 3 5 15 4 8 32 Example 2: 5 9 45 3 6 10 60 4 Answers should always be given in simplest form which means the numerator and denominator have no common factor other than 1. You can multiply first and then simplify or simplify first and then multiply. or 1 3 2 2 5 9 3 6 10 4 Division Rule for Fractions: To divide fractions, multiply the numerator by the reciprocal of the divisor. a c a d ad b d b c bc Example 3: 3 2 3 7 21 5 7 5 2 10 Recall: The reciprocal of a number n is Example 4: 2 2 1 1 10 9 9 10 45 3 1 . n Addition and Subtraction Rules for Fractions: To add or subtract fractions, you must have common denominators. If fractions have different denominators, rewrite the fractions using their least common denominator. Then add or subtract the numerators and write the result over the common denominator. Simplify if needed. a b a b c c c Example 5: 3 1 31 4 5 5 5 5 Example 6: 5 1 5 3 5 3 2 9 3 9 9 9 9 a b a b c c c 1 Recall: A mixed number is the sum of an integer and a fraction, such as 2 . 3 For our purposes in Algebra, all mixed numbers should be written as a single fraction. 1 1 2 1 6 1 7 2 3 3 1 3 3 3 3 Example 7: 2 Example 8: 3 3 3 3 15 3 18 3 3 5 1 5 5 5 5 5 4 REVIEW SECTION 3 – THE REAL NUMBER SYSTEM All of the math problems you have solved so far have used numbers from the Real Number system. The set of numbers in the Real Number system is often abbreviated by the symbol R. If you were to point to any location on a number line, that location could be represented by a Real Number. As a result, since there are an infinite number of locations on a number line, then the set of R is infinitely large. There are several categories of numbers, or subsets, within the set of R. If you compare the definitions carefully, you will see that each subset is built upon the previous subset of numbers, each with its own symbol. They include: Definition of Set Name Symbol Natural (Counting) N Whole W Integer Z Rational Q Natural numbers are sometimes called Counting numbers since they represent the numbers you would use to count out something such as the number of apples from a fruit stand in a supermarket. The set of N is given in set notation as 1,2,3, 4,... . The three periods indicate that the set continues infinitely with the given pattern. The set of Whole numbers is the same as the set of N but also includes 0. The set of W is given in set notation as 0,1,2,3, 4,... . The set of Integers is given by the set of W and their opposites. The set of Z is given in set notation as ... 3, 2, 2,0, 1, 2, 3,... . Notice that this set continues infinitely in both the positive and negative directions. The set of Rational numbers is defined as any number that can be written as a fraction where both the numerator and denominator are Integers. Some examples of Rational numbers are: 1 9 , , 22 2 5 Irrational I 22 0 rewritten as , 0 rewritten as , etc. 1 1 Notice that the N, W, and Z sets can therefore also be classified as Rational numbers. A number that is not a Rational number is considered to be Irrational. Examples of Irrational Numbers are 2, , 0.4257349369... (no pattern) 5 Sometimes it is convenient to represent the relationship between all of the sets within the Real Number system by using either a Venn Diagram or a “Family Tree” Diagram: THE REAL NUMBERS SYSTEM, R Venn Diagram “Family Tree” Diagram R R Q Q Z I I Z W W N N To name the sets of numbers to which a specific number belongs, use the following process: 1) Since all numbers used so far are Real, always start by listing R. (During Algebra II, you will learn about a different number system that uses what are called Imaginary Numbers) 2) Continue by considering whether the number meets the requirements for a Natural number. If it is a Natural number, then it may also be automatically classified as W, Z and Q since Natural numbers are subsets of each of these other sets. 3) If it is not a Natural number, decide if it meets the requirements for a Whole number. If it is a Whole number, then it may automatically be classified as Z and Q as well. 4) If it is not a Whole number, repeat the comparison for Integers. 5) If it is not an Integer but is written as a fraction, determine if both the numerator and denominator are Integers. If they are Integers, then the number is Rational. If either the numerator or denominator is not an Integer but the fraction can be simplified to Integers in both positions, then the number is Rational. If the fraction cannot be simplified to the quotient of two integers, then the number is Irrational. 6) If the number is not a fraction and does not meet any of the requirements for N, W, Z, or Q, then it must be Irrational. 6 Name all of the number sets to which the following numbers belong: Example 1: 17 R N W Z Q All numbers considered so far are Real. 17 is a “counting” number so it is Natural. All Natural numbers are Whole numbers. All Natural numbers are Integers. All Natural numbers are Rational. (can be rewritten as 17 . 1 Example 2: 0 I Not Irrational since it is Rational. R N W Z Q All numbers considered so far are Real. Not Natural since 0 is NOT a “counting” number. 0 is first number in the Whole number set. All Whole numbers are Integers. All Whole numbers are Rational (can be rewritten as 0 . 1 Example 3: Example 4: 1 3 4 2 3 I Not Irrational since it is Rational. R All numbers considered so far are Real. N W Z Not Natural since it is not a “counting” number. Not a Whole number. Not an Integer. On a number line, 1 3 is Q between the integers –2 and –1. Rational because when rewritten as I the numerator and denominator are Integers. Not Irrational since it is Rational. 4 7 4 , both The approximate value of this number as determined from R N W Z Q I a calculator is 0.471404521… All numbers considered so far are Real. Not Natural since it is not a “counting” number. Not a Whole number. Not an Integer. On a number line, this value is between the integers 0 and 1. Not Rational because when though it is written as a fraction, the numerator 2 is not an Integer. Irrational since it is not Rational. 7 A final word about Rational vs. Irrational Numbers… RATIONAL: If a number is Rational, then its decimal equivalent value is either a) terminating or b) non-terminating with a repeating pattern. For example: a) 2 5 is equal to 0.4 which is a terminating decimal (only zeros appear after the 4). b) 1 is equal to 0.333… or 0.3 . This decimal is non-terminating (goes on 3 infinitely), but has a repeating pattern. IRRATIONAL: If a number is Irrational, then its decimal equivalent value is non-terminating and does not have a repeating pattern. For example: c) is equal to 3.141592564… which is a non-terminating decimal and does not have a repeating pattern. d) 2 is equal to 1.414213562… and is therefore Irrational. *** CAUTION! *** SQUARE ROOTS: Sometimes we jump to the conclusion that anytime we see a square root sign (radical symbol) that the number must be Irrational. But if the number under the square root sign (radicand) is a perfect square, then the number is, in fact, Rational as well as Natural, Whole and Integer. Example 5: 24 Example 6: 121 Example 7: 25 2 Since 24 is not a perfect square, this number is Irrational. Since 121 is a perfect square of 11, this number is Rational. Since 25 is a perfect square of 5 and this fraction simplifies to Example 8: 15 7 5 2 , it is Rational. Since 15 is not a perfect square, this entire fraction is considered Irrational. 8 REVIEW SECTION 4 - PROPERTIES OF REAL NUMBERS Properties of Addition: Property Description Closure If two or more numbers are added, then the sum of those numbers will be a member of the same number set as the addends. Associative Addends can be regrouped without affecting the value of the expression. Commutative The order of addends can be changed without affecting the value of the expression. Identity Element The Identity Element of addition is (Additive Identity) 0 (zero) – adding 0 to any number yields the same number. Inverse Element The Inverse Element of addition is (Additive Inverse) an Opposite – adding a number and its opposite will yield the identity element 0. Properties of Multiplication: Property Description Closure Associative Commutative Identity Element (Multiplicative Identity) Inverse Element (Multiplicative Inverse) (Reciprocal) If two or more numbers are multiplied, then the product of those numbers will be a member of the same number set as the factors. Factors can be regrouped without affecting the value of the expression. The order of factors can be changed without affecting the value of the expression. The Identity Element of Multiplication is 1 (one) – multiplying any number by 1 yields the same number. The Inverse Element of Multiplication is the Reciprocal – Multiplying any number by its reciprocal will yield the identity element of 1. 9 Example If a and b are Real numbers, then the sum of a and b is also a Real number. (a b ) c a (b c ) a b b a a 0 a a a 0 Example If a and b are Real numbers, then the product of a and b is also a Real number. (a x b) x c = a x (b x c) axb=bxa ax1=a a 1 1 a Distributive Property: Property Distributive Example Multiplication of a sum or difference of two numbers by another number. Properties of Equality Property Reflexive Symmetric Transitive Substitution Addition Multiplication 3(x + y) = 3x + 3y Description a a a x (b + c) = ab + ac a x (b – c) = ab - ac Description / Example If a = b, then b = a If a=b and b=c, then a=c If a= b and m = b, then a = m If a= b and c is a real number, then a + c = b + c If a= b and c is a real number, then ac = bc REVIEW SECTION 5 – SOLVING LINEAR EQUATIONS 1) Eliminate fractions from the equations using LCD 2) Distribute scalers (multiply using Distributive Property) 3) Undo +/4) Undo 5) Undo ( ) Example 1: 2 f 7 2f 14 2f 14 2f 14 14 14 Distribute Subtract 2f Since -14 = -14 is always true, the original equation is an identity and the solution set includes all Real numbers. Example 2: 20 3x 3x 5 20 5 Add 3x Since 20 5, there are no solutions that make it true. Therefore, there is no solution for this equation (often given by the Greek symbol phi ). 10 Example 3: 2 x 5 10 3x 2 2x 10 10 3x 2 Distribute Combine like terms Subtract 3x Divide by -1 2x 3x 2 x 2 x 2 Example 4: 1 1 16 6x 9 15x 2 3 1 1 6 16 6x 6 9 15x Clear the fractions using LCD of 6 2 3 Simplify 3 16 6x 2 9 15x 48 18x 18 30x 18x 30 30x 48x 30 30 48 5 x 8 x Distribute Add -48 Add -30x Divide by -48 Reduce to simplest terms. Example 5: 1 2 2n 3n 5 3 1 2 15 2n 15 3n 5 3 3 30n 10 45n Multiply each side by 15 7 15n 7 n 15 Example 6: 3 2 5 1 x x 2 3 6 4 1 3 2 5 12 x 12 x 4 2 3 6 18 8x 10x 3 15 18x 5 x 6 11 Multiply each side by 12 LCD: 12 . REVIEW SECTION 6 – SOLVING INEQUALITIES IN ONE VARIABLE The graph of an inequality in one variable is the set of points on a number line that represent all solutions of the inequality. Equivalent Inequalities are inequalities that have the same solution. For all real numbers, a,b and c: Addition Prop. of Inequalities If a › b , then a + c › b + c If a ‹ b , then a + c ‹ b + c Subtraction Prop. of Inequalities Mult. Prop. of Inequalities If a › b , then a - c › b – c If a ‹ b , then a - c ‹ b – c For c › 0 If If If If For c < 0 Division Prop. of Inequalities For c › 0 a›b, a‹b, a›b, a‹b, then then then then ac › ac ‹ ac ‹ ac › If a › b , then If a ‹ b , then For c ‹ 0 If a › b , then If a ‹ b , then NOTE: When you multiply or divide by a negative number number “doing the work” is negative), the direction of the inequality sign changes. a b › c c a b ‹ c c a b ‹ c c a b › c c (i.e. the Graphing Inequalities Example 1: Graph 3 › x Solution. Rewrite as x ‹ 3 Use an open circle for the ‹ or › inequality symbols. -2 -1 0 1 2 3 4 Example 2: Graph x ≥ 4 Use a closed circle for the ≤ or ≥ inequality symbols. 2 12 3 4 5 6 7 8 bc bc bc bc Solving Inequalities and Graphing Solution Example 3: Solve and Graph x-7 › -6 x›1 Graph -2 -1 Add 7 to each side 0 1 2 3 4 Example 4: Solve and Graph x+2 ≤ 7 x≤5 Graph 2 3 Subtract 2 from each side 4 5 6 7 8 Compound Inequalities A compound inequality consists of two inequalities connected by an “and” or an “or” statement. Example 5: x is greater than -4 and less than or equal to -2. -4 ‹ x ≤ -2 Example 6: x is greater than -3 and less than -1 -3 ‹ x ‹ -1 Note that the manner in which the “and” type of compound inequality is written n Examples 5 and 6 implies that the value of x is between the lower (left) and upper (right) values of the compound inequality. Example 7: x is greater than zero or less than -3 x ‹ -3 or x › 0 Note that an “or” type of compound inequality must be written as two separate inequalities joined by “or.” This type of inequality cannot be written as a continuous “string” as shown for “and” type inequalities in Examples 5 and 6. 13 Graphing an “or” Type Compound Inequality The graph of an “or” type of inequality represents the union of the two separate inequalities (i.e. the solution set includes points that work in one inequality, the other inequality or both inequalities). Example 8: Graph x ‹ -2 or x › 2 -3 -2 -1 0 2 1 3 Graphing an “and” Type Compound Inequality The graph of an “and” type of inequality represents the intersection of the two separate inequalities (i.e. the solution set includes points that must work in both inequalities). Example 9: Graph 2 x 3 This compound inequality is the same as x ≥ -2 and x ‹ 3 -3 -2 -1 0 2 1 3 More Examples – Solving Inequalities with Various Strategies Example 10: Solve and Graph x 5 3 x › 15 0 Example 11: Solve and Graph 5 Multiply both sides by 3 to “clear” fractions. 10 15 20 -4x ≤ 8 x ≥ -2 -3 14 -2 25 30 Divide by –4 to solve for x. Since dividing by a negative number, direction of inequality sign must be changed. -1 0 1 2 3 Example 12: Solve and Graph 3n + 2 › 14 3n › 12 n›4 2 Example 13: Solve and Graph 4 5 4(x - 1) ≥ 8 4x – 4 ≥ 8 4x ≥ 12 x≥3 1 Example 14: Solve and Graph 3 Add -2 Divide by 3 2 3 -3 -2 7 8 Distribute Add 4 Divide by 4 4 11 – 2x ≥ 3x + 16 -2x ≥ 3x + 5 -5x ≥ 5 x ≤ -1 -4 6 -1 5 6 7 Subtract 11 Subtract 3x Divide by -5 0 1 2 Example 15: Solve and Graph an “or” Compound Inequality 5x + 1 ‹ -4 or 6x – 2 ≥ 10 Solve each 5x ‹ -5 or 6x ≥ 12 inequality x ‹ -1 or x≥2 separately. fractions. -3 -2 -1 0 1 2 3 Example 16: Solve and Graph an “and” Compound Inequality -9 ≤ -4x – 5 ‹ 3 Implied “and” Inequality. -4 ≤ -4x ‹ 8 Add 5 to each expression. 1 ≥ x › -2 Divide each expression by –4; change direction of inequality signs. -2 ‹ x ≤ 1 Rewrite solution. -3 -2 -1 0 1 2 3 Note: Compound inequalities with implied “and” are always expressed with the lower value to the left [low -> high]. 15 REVIEW SECTION 7 – SLOPE OF LINEAR EQUATIONS When graphing a linear equation, the resultant line has a certain amount of “steepness” associated with it. In order to quantify the amount of steepness, we define the “slope” of the line as the following ratio: Slope = m = Change in y direction Rise . Change in x direction Run The terms “Rise” and “Run” come from the phrase “Rise over Run” which is commonly used in carpentry to describe the dimension of the vertical portion of a step (Rise) as compared to the dimension of the horizontal or tread portion of the step (Run). When taken together, Rise over Run tells the story of the slope, or steepness, of the steps. The slope of a linear equation is the same at any point along the graph of the equation. 7A. DETERMINING SLOPE DIRECTLY FROM A GRAPH 1) Identify the coordinates of a point on the graph where the line crosses at the intersection of grid lines on the graph paper. 2) Identify a second point, which also crosses at the intersection of grid lines. 3) Starting at the first point, draw a step using only vertical and horizontal moves that will take you to the second point. The amount of movement in the vertical direction is the “change in y” and the amount of movement in the horizontal direction is the “change in x.” Use these values to calculate the slope as shown above. NOTE: Movement Movement Movement Movement is a move in the positive y direction is a move in the negative y direction is a move in the positive x direction is a move in the negative x direction 16 Example: From the graph shown, two convenient points are selected which cross at the intersection of grid lines on the graph paper. Since slope is the same at all points along the graph, the size of the “step” created does not matter. x 2 y 3 Based on a movement of +3 in the y direction and +2 in the x direction, the slope of this equation would be 3 . 2 7B . DETERMINING SLOPE FROM TWO POINTS Since the slope represents the ratio of change in y direction to change in x direction, then slope may be calculated from two ordered pair solutions (x1, y1) and (x2, y2) for the equation by the following formula: Difference in y coordinates y2 y1 y Slope = m = Difference in x coordinates x2 x1 x Note: The triangular symbol ( ) is the Greek letter Delta and is used in Math and Science to represent change. In this case, represents the change in x or y coordinates. Example: If the points (4,2) and (-1, 5) are two solutions of a linear equation, then the slope of that equation may be calculated as follows: The ordered pair (4,2) is arbitrarily labeled Point1 and (-1,5) is labeled Point2. The x and y coordinates for each point are labeled using subscripts to keep track of the numbers that will be used in the slope calculation. m Point 1 Point 2 ( 4, 2 ) x1 , y1 ( 1, 5 ) x2 , y2 change in y 52 3 change in x 1 4 5 17 7C. DETERMINING SLOPE FROM THE SLOPE-INTERCEPT FORM OF AN EQUATION If an equation is written in the slope intercept form of y=mx+b, then the slope may be obtained directly from m, the numerical coefficient of x. Example: Given the equation y 3x 1 , the slope of this equation will be 3 3 . or 1 1 (See the Section 8A, Graphing Linear Equations using a Point and Slope for more information on equivalent forms for the value of slope) 7D. SPECIAL VALUES OF SLOPE The slope of a horizontal line is always zero (0). Given any horizontal line, the y-coordinates for all points on the line are identical. As a result, since y 0 for any given x , then the slope of a horizontal line is always equal to zero and the equation of the line becomes simply y = “the y-coordinate.” mhorizontal y 0 0 x x The slope of a vertical line is considered to be “Undefined” and is sometimes called “No Slope.” Given any vertical line, the x coordinates for all points on the line are identical. As a result, since x 0 for any given y , then the slope is considered “Undefined” since dividing by zero ( x 0 ) in the slope calculation is prohibited. The equation of a vertical line then becomes simply x = “the x-coordinate.” mvertical y y Undefined x 0 18 REVIEW SECTION 8 – GRAPHING LINEAR EQUATIONS The graph of a linear equation is a straight line. When you first started to graph linear equations, you probably picked several values of x, calculated the corresponding values of y using the given equation, plotted the points and then connected the points with a line. You have also learned to graph linear equations by three other methods: a) using a given point on the line and slope, b) using slope and y-intercept and c) using x and y-intercepts. In Algebra 2H, you will be expected to be able to use these three “shortcut” methods to graph linear equations. You will also be expected to develop a linear equation from only a graph of the equation. 8A. GRAPHING LINEAR EQUATIONS USING A POINT AND SLOPE 1) If given a point on a line and the slope of the line through that point, the location of the given point represents a starting point for drawing the graph. Plot the given point. 2) The slope, commonly represented by the variable m, indicates the direction to “move away” from this given point in a stepwise manner. Using the location of the given point as a starting point, find a second point on the graph by moving away from the given point using the vertical and horizontal components given by the slope. Find one point on either side of the given point to confirm the trend indicated by slope. 3) Draw a straight line through given point and the points constructed through use of the slope. A few notes on interpreting “direction of movement” from slope (m) 2 If m = an integer value like 2, rewrite it as to represent a move of 2 in 1 the positive y direction ( ) and 1 in the positive x direction (). Remember that this value of slope could also be represented by 2 which would be 2 in 1 the negative y direction () and 1 in the negative x direction (). If m is a negative value like 2 , remember that you can associate the 3 2 2 negative sign with either the numerator or the denominator to 3 3 obtain the correct direction of movement from a given point. 19 EXAMPLE: Graph the equation of a line that goes through the point (2, -1) and has a slope of 3 . 4 Step 1: Graph the given point in Quadrant IV as shown on the graph below. Step 2: Plot additional points based on the stepwise movement given by the slope. Since m = 3 , then move away from 4 the given point by moving 3 units in the negative y direction and then 4 units in the positive x direction (i.e. y 3, x 4 ). Another option is to move 3 units in the positive y direction followed by 4 units in the negative x direction (i.e. y 3, x 4 ). Step 3: Draw a straight line through the given point and the constructed points. y x 4 y 3 x Starting point at (2, -1) y 3 x 4 A reminder about “Special Cases” where Slope = 0 or is “Undefined” SLOPE = 0: The graph of an equation such as y= (some value) is always represented by a horizontal line and is commonly referred to as 20 a Constant Function. Since all points along a horizontal line have the same value for the y-coordinate, the value of y is always equal to zero and as a result, the slope of this line is always zero (0). EXAMPLE: Graph the equation of a line that goes through the point (4, -3) and has a slope of 0. What is the equation of this line? 10 8 6 4 2 -10 -8 -6 -4 -2 2 4 6 8 10 -2 -4 -6 -8 -10 SLOPE = UNDEFINED: The graph of an equation such as x= (some value) is always represented by a vertical line. Since all points along a vertical line have the same x-coordinate, the value of x is always equal to zero and as a result, the slope of this line is always “Undefined.” An undefined slope is sometimes also described as “No Slope” or is represented by the Greek symbol phi ( ). EXAMPLE: Graph the equation of a line that goes through the point (3, 2) and has an undefined slope. What is the equation of this line? 10 8 6 4 2 -10 -8 -6 -4 -2 2 -2 -4 -6 -8 -10 21 4 6 8 10 8B. GRAPHING LINEAR EQUATIONS BY SLOPE AND Y-INTERCEPT SLOPE-INTERCEPT FORM: m = slope y mx b where b = y-intercept 1) If the equation is not in the “slope-intercept” form of y = mx+b, complete the necessary transformations to get it into this form. 2) The y-intercept is given by the value of b in the equation and is the starting point for completing this graph. This point would be graphed on the y-axis as the ordered pair (0, y-intercept). 3) The slope is given by the value of m and indicates the direction to move away” from the y-intercept in a stepwise manner. Using the y-intercept as a starting point, find a second point on the graph by moving away from the y-intercept. Find one point on either side of the y-intercept to confirm the trend indicated by slope. 4) Draw a straight line through y-intercept and constructed points. EXAMPLE: Graph: 2x 3y 6 Step 1: Convert to slope intercept form: 2x 3y 2x 6 2x Addition Property of Equality 1 1 3y 2x 6 3 3 2 y x 2 3 . Multiplication Property of Equality Step 2: Identify the key graphing parameters and graph: y-intercept: Since b = 2. the y-intercept is located at (0, 2). slope: Since m = x 3 y 2 Starting point is at y intercept (0, 2) y 2 2 3 , then “move away” from the y- intercept starting point by moving 2 units in the positive y direction and then 3 units in the positive x direction. It could also mean a move of 2 units in the negative y direction and then 3 units in the negative x direction since 23 = 23 . x 3 22 REVIEW SECTION 9 – WRITING LINEAR EQUATIONS While the slope intercept form of a linear equation, y mx b , is one of the most convenient forms to use in order to easily graph a linear equation, the point-slope form of a linear equation is the preferred format to use when writing linear equations based on given information like slope of the line and the coordinates of a solution point on the line. The point-slope form of a linear equation is shown below: y y1 m x x1 where : m = slope x1 , y1 = coordinates of an ordered pair on the line (and therefore, part of solution set) Upon careful examination, you will see that the point-slope form of a linear equation is nothing more than an algebraic transformation of the slope formula for a general value of x and y: m y y1 ; x x1 Cross multiply to obtain: y y1 m x x1 9A. WRITING LINEAR EQUATIONS GIVEN A POINT AND A SLOPE Example 1: Write the equation of a line that has a slope of through the point 3, 1) . Given : m 3 ; 4 x1 3; y1 1 y y1 m x x1 y 1 34 x 3 3 9 x 4 4 3 9 y x 1 4 4 3 5 y x 4 4 y 1 23 3 and goes 4 9B. WRITING LINEAR EQUATIONS GIVEN TWO POINTS Example 2: Write the equation of a line that goes through the points 2, 5 and 6, 9 . The only difference between this problem and the previous problem is that slope has not been calculated for you. The starting point for this problem is then to first find the slope of the line and then find the equation in the same manner as demonstrated in the last example: Given: x1 2 y1 5 Slope = m = x2 6 y2 9 y y y1 9 5 14 7 2 x x2 x1 6 2 4 2 y y1 m x x1 7 2 y 5 x 2 y 5 7 x 7 2 7 x 7 5 2 7 y x 12 2 y 24 9C. WRITING EQUATIONS FOR PARALLEL & PERPENDICULAR LINES Parallel lines never intersect and therefore the slopes of these lines must be equal. Perpendicular lines however, intersect at a 90 angle. The slopes of perpendicular lines are negative reciprocals of each other. Example 5: 3 2 The equation of a line is y x 3 and therefore its slope is The slope of a parallel line is therefore also 3 . 2 3 . 2 The equation of a line parallel to the original line is y 3 3 x 2 or y x 13 etc ... 2 2 2 3 The slope of a perpendicular line is . The equation of a line perpendicular to the original line is 2 y x 7 or 3 2 y x 9 etc ... 3 1 3 Example 6: Find the equation of a line that is parallel to y x 4 and goes through the point (-3,7). 1 3 1 y 7 x 3 3 1 y 7 x 1 3 1 y x 8 3 y 7 x (3) Slope is the same. Use Point-Slope formula to set up and transform to Slope-Intercept form. 3 5 Example 7: Find the equation of a line that is perpendicular to y x 4 and goes through the point (2,-9). 5 y 9 3 x 2 5 10 x 3 3 5 10 y x 9 3 3 5 37 y x 3 3 y 9 25 Slope is the negative reciprocal. Use Point-Slope formula to set up and transform to Slope-Intercept form. REVIEW SECTION 10 – SOLVING SYSTEMS OF EQUATIONS Vocabulary: Two or more linear equations in the same variables represent a system of linear equations or a linear system. Three possible scenarios exist when solving a system of equations: 1) One unique ordered pair satisfies all of the equations in the system; the solution is given by that ordered pair, (a, b). 2) An infinite number of ordered pairs satisfy all of the equations in the system. In this case, the graphs of both equations are the same line. 3) No ordered pairs satisfy all of the equations; the graphs of these equations are parallel and therefore do not intersect. As a result, the system has no solution, given by the Greek symbol . If the solution to a system of linear equations in two variables is an ordered pair of numbers (a, b), then substitution of this ordered pair into either one of the equations in the system (x = a and y = b), results in a true statement. The point (a,b) lies on the graph of each equation and is the point of intersection of the graphs. 10A. SOLVING SYSTEMS OF EQUATIONS GRAPHICALLY Example: -3x + y = -7 2x + 2y = 10 Solution: Rewrite each equation in slope-intercept form. 1) -3x + y = -7 y = 3x –7 Slope: 3 y int: (0. –7) 2) 2x + 2y = 10 y = -x + 5 Slope: -1 y int: (0, 5) Graph of Equation # 2 Graph of Equation # 1 26 Solution to system is given by coordinates of intersection of the two equations. In this case, the solution is (3, 2) 10B. SOLVING SYSTEMS OF EQUATIONS BY LINEAR COMBINATION (also known as Elimination) The objective in this method is to get the coefficients of one variable to be opposite numbers. Example: Solve the system: 4x - 3y = 11 3x + 2y = -13 To eliminate the y 4x - 3y = 11 3x + 2y = -13 Multiply by 2 Multiply by 3 8x - 6y = 22 9x + 6y = -39 Add the equations Solve for x 17x = -17 x = -1 Substitute - 1 for x in either of the original equations and solve for y. 3x + 2y = -13 3(-1) + 2y = -13 – 3 + 2y = -13 2y = -10 y = -5 Substitute –1 for x Simplify Add 3 to each side Solve for y The solution is ( -1 , -5 ) 27 10C. SOLVING SYSTEMS OF EQUATIONS BY SUBSTITUTION The method of solving systems by substitution should be considered when at least one of the variables in the system has a coefficient of one (1) as demonstrated in the following example: Example: x+y=1 2x –3y = 12 Solution: Solve for y in the first equation y = -x + 1 Substitute –x + 1 for y in the second equation and solve for x. 2x – 3y = 12 2x – 3(-x + 1) = 12 2x + 3x – 3 = 12 5x – 3 = 12 5x = 15 x=3 Substitute –x + 1 for y Distribute the –3 Combine like terms Add 3 to each side Divide each side by 5 Find the value of y by substituting 3 for x in an original equation. 3+y=1 y = -2 or 2(3) – 3y = 12 6 – 3y = 12 - 3y = 6 y = -2 28 Solution: ( 3, -2) REVIEW SECTION 11 – INEQUALITIES IN TWO VARIABLES AND SYSTEMS OF INEQUALITIES 11A. GRAPHING A LINEAR INEQUALITY IN TWO VARIABLES Any point in shaded region is a member of the solution set. Example: Graph x – y < 2 The corresponding equation is x – y = 2. In slope-intercept form, this equation is y= x – 2. Graph this line using a slope of 1 and y-intercept of -2 . Use a dashed line to show that the points on the line are not solutions since the original inequality is just “ ”, not “ ”. y Test Point (0, 0) Use the coordinates of a point that is not on the line to determine the region in which the original inequality will be satisfied. For ease of calculation, always consider using the origin (0,0) as the test Points on line are point unless it is on the line. Substituting the values of the excluded from solution set in this example coordinates into the original inequality will generate either a (dotted line). true or false statement. In this example, (0,0) generates a true statement (0 – 0 < 2 is true) and therefore, all points in the region above the line (where the test point is located) are included in the solution set. If the coordinates had generated a false statement, then that region would be excluded from the solution set. This area is then shaded to show the region of the graph representing the solution set (i.e. the solution set for this inequality is the set of all points above the graph of y = x – 2. NOTE: The type of line used for the boundary between solution points and non-solution points always depends on the type of inequality presented in the original problem: Inequality Symbol or or “Boundary” line type Dotted or dashed line Solid line 29 REVIEW SECTION 12 – RULES OF EXPONENTS Vocabulary Power of a number: A product of equal factors. For example, 2 2 2 , means the third power of 2. Base of a power: The number that is used as a factor. For example, 2 is the base of 23 . Exponent: In a power, the number that indicates how many times the base is used as a factor. For example, 3 is the exponent in 23 . Exponential form: The power of a number written using a base and an exponent. The expression 23 is the exponential form of 2 2 2 . Note: An exponent goes with the base immediately preceding it unless parentheses indicate otherwise. Example 1: 3y 2 means 3 y y 2 is the exponent of the base y. 3y 2 is the exponent of the base 3y. 2 means 3y 3y Product of Powers: When two powers with the same base are multiplied, add the exponents. a m a n a m n Example 2: x 2 x 5 x 2 5 x 7 Think: x is being used as a factor a total of 7 times. Example 3: 32 33 323 35 Example 4: 6c 3c 5 6c 1 3c 5 6 3 c 15 18c 6 Power of a Power: When a power is raised to a power, multiply exponents. a m n Example 5: x x 76 x 42 Example 6: 2 234 212 7 6 3 4 a mn 30 Power of a Product: When a product is raised to a power, raise each factor to the power and then multiply. ab 5 Example 7: 2x Example 8: 6x 2 m a mb m 5 2 x 5 32x 5 y 5 6 x 2 y 5 216x 6y 15 3 3 3 3 Quotient of Powers: When two powers with the same base are divided, subtract the exponents. am If m n , a m n an am 1 If n m, n m n a a Example 9: x8 x x x x x x x x x8 5 x 3 5 x x x x x x Example 10: x5 1 1 8 5 3 8 x x x Example 11: Think: Where are the most factors of x? How many extra factors? 4a 3b 2 a2 16ab 3 4b Power of a Quotient: When a quotient is raised to a power, raise the numerator and the denominator to that power. Then divide and simplify. m m a a bm b Example 12: 5 25 32 32 2 5 5 4 20 3x 3x 4 35 x 4 243x 31 Zero Exponents: If a is a real number not equal to zero, then a 0 1 . (The expression 0 0 has no meaning!) Example 13: 250 1 Example 14: 5x 0 5 1 5 but 5x 0 Remember: An exponent goes with the base immediately preceding it, unless otherwise indicated by parentheses. 1 Negative Exponents: If a is a nonzero real number and n is a positive 1 integer, then a n n . Negative exponents mean reciprocals! All rules for a positive exponents also hold for negative exponents. 1 1 3 2 8 Note: Negative exponents do not mean negative numbers! Example 15: 23 Example 16: x Example 17: 2x Example 18: x9 x 9 x 2 x 11 2 x Example 19: x5 1 x 512 x 7 7 12 x x Example 20: 4x 5 4x 5 3) 2x 8 3 2x 2 1 2 2 4 x 1 2 x 2 24 x 2 16x 8 4 16 x8 Remember: An exponent goes with the base immediately preceding it, unless otherwise indicated by parentheses. Note: The preferred form of a simplified expression has only positive exponents. 32 REVIEW SECTION 13 – OPERATIONS WITH POLYNOMIALS Vocabulary Monomial: An expression that is either a numeral, a variable, or the product of a numeral and one or more variables. Also called terms. Examples: 13, m, 8c, 2xy, 5p 2q Coefficient: In a monomial, the number preceding the variable. When a monomial does not have a written coefficient, its coefficient is 1. Polynomial: A sum of monomials. Example: x 2 3x y 2 2 Binomial: A polynomial that has exactly two terms. Example: 2x 5 Trinomial: A polynomial that has three terms. Example: a 2 2ab b 2 Similar or Like Terms: Two monomials that have exactly the same variable names. Examples: 3xy and 7xy , 5ab 2 and ab 2 Addition of Polynomials: To add two or more polynomials, combine the coefficients of the like-terms. Example 1: 2x 2 5xy 6y 2 8x 2 6xy y 2 10x 2 11xy 5y 2 Subtraction of Polynomials: To subtract polynomials, change the second polynomial to its opposite and then add to the first polynomial. Example 2: 3x 3x 2 2 6xy 2y 2 5 x 2 5xy 6y 2 3 6xy 2y 2 5 x 2 5xy 6y 2 3 4x 2 11xy 8y 2 2 Multiply a Polynomial by a Monomial: Multiply each term of the polynomial by the monomial, apply the rules for exponents as appropriate. Example 3: 2x 3x 2 2x 1 6x 3 4x 2 2x 33 Multiply a Binomial by a Binomial: Multiply each term of the first binomial by each term of the second binomial using the distributive property. “FOIL” (First times First, Outer product, Inner Product, Last times Last) L F a b c d I O Example 4: 3x 22x 5 6x 2 15x 4x 10 6x 2 11x 10 Multiply a Polynomial by a Binomial: Use the distributive property twice to multiply each term of the binomial times each term of the polynomial. Then combine like-terms. Example 5: 2x 3 x 2 4x 5 2x 3 8x 2 10x 3x 2 12x 15 2x 3 11x 2 2x 15 Special Products: Difference of Two Squares: Squares of Binomials: a b a b a 2 b 2 2 a b a 2 2ab b 2 2 a b a 2 2ab b 2 Example 6: 2n 32n 3 4n 2 9 Example 7: x Example 8: 5x Perfect Square Trinomials 4 x 2 2(x 4) 42 x 2 8x 16 2 2 2 2 2 5x 2(5x 2) 2 25x 2 20x 4 34 REVIEW SECTION 14 – FACTORING POLYNOMIALS Factoring polynomials – to write a polynomial as the product of polynomials of lower degree. A polynomial with integral coefficients whose greatest common factor is 1 and cannot be written as the product of polynomials of lower degree is called prime. A polynomial is factored completely when each polynomial factor is prime. Guidelines for Factoring 1) Factor out the greatest monomial factor, GCF, first! The greatest monomial factor is the greatest coefficient and greatest degree of each variable common to every term in the polynomial. Example 1: 2) The greatest monomial factor of 6x 5 4x 3 8x is 2x since 6x 5 4x 3 8x 2x 3x 4 2x 2 4 . Look for special patterns: Difference of Squares: a 2 b 2 a b a b The difference of squares is a binomial difference whose two factors are perfect squares as its name suggests. To factor, take the square root of each term and write as the product of the difference of the square roots times the sum of the square roots. Example 2a: 25x 2 121 5x 11 5x 11 a 2 2ab b 2 a b 2 Perfect Square Trinomial: a 2 2ab b 2 a b 2 To determine if a trinomial is a perfect square, both the first and last terms should be perfect squares and the coefficient of the middle term should be twice the product of the square roots of the first and last terms disregarding the sign. Example 2b: 4x 2 12x 9 is a perfect square trinomial because 2 2 2 4x 2 2x , 9 3 and 12x 2 2x 3 so 4x 2 12x 9 2x 3 . 35 Example 2c: 16x 2 20x 25 is not a perfect square trinomial Even though 16x 2 and 25 are perfect squares, the coefficient of the middle term should be 2 4x 5 40x . This is a prime polynomial. 3) If the polynomial is a trinomial that does not fit a special pattern, look for a pair of binomial factors. For x 2 bx c , find two factors of c whose sum is b. Example 3a: x 2 6x 8 x 2 x 4 since 2(4) = 8 and 2 + 4 = 6. Note the following factoring patterns: when b is positive: x ? x ? when b is negative: x ? x ? If c is positive x ? x ? If c is negative: Example 3b: Factor 10x 2 11x 3 Because the constant term is positive and the linear term is negative, the factoring pattern will be ? x ? ? x ? . Find factors of 10x 2 and factors of 3; test to see which produces –11x as a linear term. 10x 2 11x 3 5x 32x 1 36 REVIEW SECTION 14 – SOLVING QUADRATIC EQUATIONS Quadratic equations have two solutions as compared to linear equations that just have one solution. You can tell that an equation is quadratic if one of the variable terms is squared (i.e. of 2nd degree). We will be exploring a number of different methods for solving quadratic equations in Algebra 2H. You have already used one of these methods which is called the Factoring and Zero Product Property method. Factoring and Zero Product Property In the event that a quadratic equation has quadratic (squared) and linear terms (raised to the 1st power), factoring by GCF, Difference of Squares or Trinomial Factoring methods along with the use of the Zero Product Property allows easy determination of the solutions. Example 1: Solve Example 2: Solve x2 6x 8 0 ( x 4)( x 2) 0 x 4 0 or x 2 0 x 4 or x2 Factor Zero Product Property Set each factor = 0 and solve. 3x3 12 x 0 3x x 2 4 0 3x x 2 x 2 0 Factor (GCF) Factor (Diff of Sq.) Zero Product Property 3x 0 or x 2 0 or x 2 0 Set each factor = 0 x 0 or x 2 or x 2 and solve. Example 3: Solve 49 x 2 100 0 (7 x 10)(7 x 10) 0 7 x 10 0 and 7 x 10 0 10 10 x and x 7 7 Example 4: Solve 0 2 x2 x 1 0 (2 x 1)( x 1) 0 2 x 1 0 and x 1 0 1 x and x 1 2 37 Factor (Diff of Sq.) Zero Product Property Set each factor = 0 and solve. Factor Zero Product Property Set each factor = and solve REVIEW SECTION 15- RADICAL EXPRESSIONS Radical Expression: An expression of the form a . The symbol, , is called a radical sign and the expression under the radical sign, “a”, is called the radicand. Square root: If a 2 b , then a is a square root of b. (Note: Negative numbers do not have square roots in the set of real numbers.) Symbols: 64 8 64 8 indicates the nonnegative or principal square root of 64 indicates the negative square root of 64 64 8 indicates both square roots of 64 I. Simplifying Radicals: To simplify a radical expression, find the square root of any factors of the radicand that are perfect squares. (If you cannot see any squares, you can use prime factorization of the radicand.) Product Property of Square Roots For any nonnegative real numbers a and b: ab a b Example: 49 4 9 Quotient Property of Square Roots For any nonnegative real number a and any positive real number b: a a b b Example: Example 1: 256 4 64 4 64 2 8 16 Example 2: 50 25 2 25 2 5 2 5 2 Example 3: Example 4: 2 80 2 16 5 2 4 5 8 5 169 169 13 100 100 10 38 36 36 4 4 II. Multiplying Radicals: Example 5: 4 2 3 4 23 4 6 Example 6: 2 3 3 48 2 3 3 48 6 144 6 12 72 III. Dividing Radicals: Example 7: 7 54 7 54 6 28 6 28 9 3 4 2 Example 8: 24 33 12 33 18 3 2 11 2 11 2 IV. Rationalizing Denominators: A radical is not considered to be in simplest form if there is a fraction under the radical sign or a radical in the denominator. Rationalizing is the process of eliminating a radical from the denominator. (Remember: a 2 a) Example 9: 1 1 1 3 3 3 3 3 3 3 Example 10: 5 5 2 5 2 2 2 2 2 V. Adding and Subtracting Radicals: Only radicals with like radicands can be combined. Example 11: 8 18 4 2 9 2 2 2 3 2 5 2 Example 12: 6 24 6 4 6 6 2 6 6 39 REVIEW SECTION 16 – LINEAR & QUADRATIC APPLICATIONS Problem Solving Process Explore the Problem Read the problem and identify what is given and what is asked. Jot down important facts from the problem. Sometimes it is helpful to draw a chart or diagram. Think about how the facts are related. Plan the solution Many different strategies may be used. If an equation will be used to solve the problem, read the problem again. Decide how the unspecified numbers relate to other given information. Write an equation to represent the relationship, making sure to identify the variables. Solve the problem This involves doing the mathematics and interpreting the answer. If an equation was written, solve the equation and interpret the solution. State the answer to the problem in words (e.g. an answer is 13 cm, not just 13). Examine the solution Check whether the answer makes sense with the conditions of the problem. If not, check your math again – sometimes, silly arithmetic mistakes are the cause. If the math is correct, then a mistake was made in “setting up” the problem. If this is the case, explore the problem again and try a different approach. Remember that not all problems in real life can be solved by using an equation. Sometimes there is no “clear-cut” method of solution. Thus, it is important to realize that there may be alternative strategies for solving problems. The four-step problem solving plan outlined above can be used to solve any type of problem using any strategy. Problem 1. 2. 3. 4. 5. 6. 7. 8. 9. Solving Strategies Draw a picture or diagram Make an organized, exhaustive list Make a chart or table Look for a pattern Write an equation Work backwards Solve a simpler form of the problem Simulate a problem Make a guess, then check 40