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1.1 Numbers • Classifications of Numbers Natural numbers Whole numbers Integers Rational numbers – can be p expressed as q where p and q are integers Irrational numbers – not rational {1,2,3,…} {0,1,2,3,…} {…-2,-1,0,1,2,…} -1.3, 2, 5.3147, 7 13 , 5 , 23 5 47 , 1.1 Numbers • The real number line: -3 -2 -1 0 1 2 3 • Real numbers: {xx is a rational or an irrational number} 1.1 Numbers • • Double negative rule: -(-x) = x Absolute Value of a number x: the distance from 0 on the number line or alternatively x x if x 0 x if x 0 How is this possible if the absolute value of a number is never negative? 1.1 Numbers • 3 > -3 means 3 is to the right on the number line -4 -3 -2 -1 0 1 2 3 4 • 1 < 4 means 1 is to the left on the number line 1.2 Fundamental Operations of Algebra • Adding numbers on the number line (-2 + -2): -4 -3 -2 -1 -2 -2 0 1 2 3 4 1.2 Fundamental Operations of Algebra • Adding numbers with the same sign: Add the absolute values and use the sign of both numbers • Adding numbers with different signs: Subtract the absolute values and use the sign of the number with the larger absolute value 1.2 Fundamental Operations of Algebra • Subtraction: x y x ( y ) • To subtract signed numbers: Change the subtraction to adding the number with the opposite sign 5 (7) 5 (7) 12 1.2 Fundamental Operations of Algebra • Multiplication by zero: x0 0 For any number x, • Multiplying numbers with different signs: For any positive numbers x and y, x( y ) ( x) y ( xy) • Multiplying two negative numbers: For any positive numbers x and y, ( x)( y ) xy 1.2 Fundamental Operations of Algebra • Reciprocal or multiplicative inverse: If xy = 1, then x and y are reciprocals of each other. (example: 2 and ½ ) • Division is the same as multiplying by the reciprocal: x y x 1 y 1.2 Fundamental Operations of Algebra • Division by zero: x For any number x, 0 undefined • Dividing numbers with different signs: For any positive numbers x and y, x y x y ( ) x y • Dividing two negative numbers: For any positive numbers x and y, x y x y 1.2 Fundamental Operations of Algebra • Commutative property (addition/multiplication) • Associative property (addition/multiplication) ab ba ab ba (a b) c a (b c) (ab)c a (bc) 1.2 Fundamental Operations of Algebra • Distributive property a (b c) ab ac (b c) a ba ca 1.2 Fundamental Operations of Algebra • PEMDAS (Please Excuse My Dear Aunt Sally) 1. Parenthesis 2. Exponentiation 3. Multiplication / Division (evaluate left to right) 4. Addition / Subtraction (evaluate left to right) • Note: the fraction bar implies parenthesis 1.3 Calculators and Approximate Numbers • Significant Digits – What’s the pattern? Number Significant Digits 4.537 0.000056 70506 40.500 4 2 5 5 1.3 Calculators and Approximate Numbers • Precision: Number 4.537 56 Precision thousandths units 56.00 40.500 hundredths thousandths • Meaning of the Last Digit: 56.5 V means the number of volts is between 56.45 and 56.55 1.3 Calculators and Approximate Numbers • Rounding to a number of significant digits Original Number Significant Rounded Digits Number 4.5371 4.5371 4.5371 4.5371 1 2 3 4 5 4.5 4.54 4.537 1.3 Calculators and Approximate Numbers • Adding approximate numbers – only as accurate as the least precise. The following sum will be precise to the tenths position. 12.123 13.1 10.1253 1.4 Exponents • Power Rule (a) for exponents: a m n a nm • Power Rule (b) for exponents: ab m a b m • Power Rule (c) for exponents: a b m m a m b m 1.4 Exponents • Definition of a zero exponent: a 0 1 (no matter wha t a is) • Definition of a negative exponent: a n 1 1 n a a n 1.4 Exponents • Changing from negative to positive exponents: a m bn m n b a • This formula is not specifically in the book but is used often: p p m n a bn b am 1.4 Exponents • Quotient rule for exponents: m a mn a n a 1.4 Exponents • A few tricky ones: 2 2 2 2 8 3 3 2 2 2 2 2 8 4 2 2 2 2 2 16 4 4 2 2 2 2 2 2 16 3 1.4 Exponents • Formulas and non-formulas: a b n a n b n (distributive property) n n a b a b n a b n a n b n , a b 2 a 2 b 2 , a 2 b2 a b ( power rule b) a b n a n b n a b 2 a 2 b 2 1.4 Exponents • Examples (true or false): t t t 4 3 12 ( t 4 ) 3 t 12 s t 2 s t 3 s t 3 3 s2 t 2 1.4 Exponents • Examples (true or false): 0 10 1 1 2 0 3 x 2 x 2 2 2 y y 23 5 2 2 2 1.4 Exponents • Putting it all together (example): 2 2 3xy 2 x y 3 3xy2 23 x 6 y 3 1 6 3(8) x 24 x y 7 5 y 23 1.4 Exponents • Another example: 3 2x y 3xy 2 1 2 3xy 2x y 3 3 6 3 x y 27 3 6 6 3 3 6 3 8 x y 2 x y 2 27 8 1 27 y x y 3 8x 3 9 2 9 3 1.5 Scientific Notation • • A number is in scientific notation if : 1. It is the product of a number and a 10 raised to a power. 2. The absolute value of the first number is between 1 and 10 Which of the following are in scientific notation? – 2.45 x 102 – 12,345 x 10-5 – 0.8 x 10-12 – -5.2 x 1012 1.5 Scientific Notation • Writing a number in scientific notation: 1. Move the decimal point to the right of the first nonzero digit. 2. Count the places you moved the decimal point. 3. The number of places that you counted in step 2 is the exponent (without the sign) 4. If your original number (without the sign) was smaller than 1, the exponent is negative. If it was bigger than 1, the exponent is positive 1.5 Scientific Notation • Converting to scientific notation (examples): 6200000 6.2 10? .00012 1.2 10? • Converting back – just undo the process: 6.203 1023 620,300,000,000,000,000,000,000 1.86 105 186,000 1.5 Scientific Notation • Multiplication with scientific notation (answers given without exponents): 4 10 5 10 4 5 10 5 8 5 108 20 103 .02 • Division with scientific notation: 4 10 4 10 5 10 5 10 12 12 4 4 80,000,000 .8 1012 4 .8 108 1.6 Roots and Radicals • a is the positive square root of a, and a is the negative square root of a because a 2 2 a and a a • If a is a positive number that is not a perfect square then the square root of a is irrational. • If a is a negative number then square root of a is not a real number. • For any real number a: a 2 a 1.6 Roots and Radicals • The nth root of a: n a is the nth root of a. It is a number whose nth power equals a, so: a n n a • n is the index or order of the radical • Example: 5 32 2 because 2 32 5 1.6 Roots and Radicals • The nth root of nth powers: – If n is even, then n – If n is odd, then n a n a n a n a a n • The nth root of a negative number: – If n is even, then the nth root is an imaginary number – If n is odd, then the nth root is negative 1.7 Adding and Subtracting Algebraic Expressions • Degree of a term – sum of the exponents on the variables 3 2 5a b degree 3 2 5 • Degree of a polynomial – highest degree of any non-zero term 5x 3x 2 x 100 degree 3 3 2 1.7 Adding and Subtracting Algebraic Expressions • Monomial – polynomial with one term 5x 3 • Binomial - polynomial with two terms 5y y 2 • Trinomial – polynomial with three terms 5 x 3x 100 3 2 • Polynomial in x – a term or sum of terms of n 4 2 the form ax for example : x 3x x 1.7 Adding and Subtracting Algebraic Expressions • An expression is split up into terms by the +/sign: 2 2 3x 4 x 3xy 35 • Similar terms – terms with exactly the same variables with exactly the same exponents are like terms: • When adding/subtracting polynomials we will need to combine similar terms: 3 2 3 2 3 2 5a b 3a b 2a b 1.7 Adding and Subtracting Algebraic Expressions • Example: (4 x 3x 5) (2 x 5 x 12) 2 2 4 x 2 3x 5 2 x 2 5 x 12 4 x 2 2 x 2 3x 5 x 5 12 2 x 8 x 17 2 1.8 Multiplication of Algebraic Expressions • Multiplying a monomial and a polynomial: use the distributive property to find each product. Example: 2 4 x 3 x 5 4 x 3 x 4 x 5 2 12 x 3 20 x 2 2 1.8 Multiplication of Algebraic Expressions • Multiplying two polynomials: x2 x 2 x 3 3x 3x 6 2 x x 2x 3 2 x3 4 x 2 5x 6 1.8 Multiplication of Algebraic Expressions • Multiplying binomials using FOIL (First – Inner – Outer - Last): 1. 2. 3. 4. 5. F – multiply the first 2 terms O – multiply the outer 2 terms I – multiply the inner 2 terms L – multiply the last 2 terms Combine like terms 1.8 Multiplication of Algebraic Expressions • Squaring binomials: x y x 2 xy y 2 x y x 2 2 xy y 2 2 2 2 • Examples: 2 2 2 2 m 3 m 23m 3 m 6m 9 5 z 1 2 5 z 25 z 12 25 z 2 10 z 1 2 1.8 Multiplication of Algebraic Expressions • Product of the sum and difference of 2 terms: x y x y x 2 y 2 • Example: 3 w 3 w 32 w2 9 w2 1.9 Division of Algebraic Expressions • Dividing a polynomial by a monomial: divide each term by the monomial 4x y 6x y 4x y 6x y 2 2 xy 3 2 2 2x y 2x y 2x y 3 2 2 3 2 2 1.9 Division of Algebraic Expressions • Dividing a polynomial by a polynomial: 2x2 x 2 2 x 1 4 x3 4 x 2 5x 8 4 x3 2 x 2 2 x 2 5x 2x2 x 4x 8 4x 2 6 1.9 Division of Algebraic Expressions x3 5x 2 7 x 3 x2 • Synthetic division: 2 1 1 5 7 3 2 6 2 3 1 1 answer is: x 2 3 x 1 1 remainder is: -1 x 3 x 1 x2 2 1.10 Solving Equations • 1 – Multiply on both sides to get rid of fractions/decimals • 2 – Use the distributive property • 3 – Combine like terms • 4 – Put variables on one side, numbers on the other by adding/subtracting on both sides • 5 – Get “x” by itself on one side by multiplying or dividing on both sides • 6 – Check your answers (if you have time) 1.10 Solving Equations • Fractions - Multiply each term on both sides by the Least Common Denominator (in this case the LCD = 4): 1 x 5 1 x 3 4 2 Reduce Fractions: 4 x 5 4 x 4 3 4 2 x 5 2 x 12 Subtract x: 5 x 12 Subtract 5: x 17 Multiply by 4: 1.10 Solving Equations • Decimals - Multiply each term on both sides by the smallest power of 10 that gets rid of all the decimals Multiply by 100: Cancel: Distribute: Subtract 5x: Subtract 50: Divide by 5: .1 x 5 .05 x .3 100 .1 x 5 100 .05x 100 .3 10 x 5 5 x 30 10 x 50 5 x 30 5 x 50 30 5 x 80 x 16 1.10 Solving Equations • Example: Clear fractions: 2 3 x x x3 Combine like terms: 4x 3x x 18 1 2 Get variables on one side: Solve for x: 1 6 7 x x 18 6 x 18 x 3 1.11 Formulas and Literal Equations • Example: d = rt; (d = 252, r = 45) then 252 = 45t divide both sides by 45: 27 3 t 5 5 45 5 1.11 Formulas and Literal Equations • Example: Solve the formula for B A 12 h(b B) multiply both sides by 2: 2 A h(b B ) divide both sides by h: A 2 h subtract b from both sides: bB A B 2 b h 1.12 Applied Word Problems • 1 – Decide what you are asked to find • 2 – Write down any other pertinent information (use other variables, draw figures or diagrams ) • 3 – Translate the problem into an equation. • 4 – Solve the equation. • 5 – Answer the question posed. • 6 – Check the solution. 1.12 Applied Word Problems • Example: The sum of 3 consecutive integers is 126. What are the integers? x = first integer, x + 1 = second integer, x + 2 = third integer x ( x 1) ( x 2) 126 3 x 3 126 3 x 123 x 41 41, 42, 43 1.12 Applied Word Problems • Example: Renting a car for one day costs $20 plus $.25 per mile. How much would it cost to rent the car for one day if 68 miles are driven? $20 = fixed cost, $.25 68 = variable cost $20 68 $.25 $20 $17 $37