Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Dividing Rational Numbers Section 2.5 Objectives • Divide rational numbers. (NS 1.2) • Simplify numerical expression by applying inverse properties of rational numbers. (AF 1.3) Words to Know • Reciprocal Two numbers whose product is 1. Also called the multiplicative inverse. To divide fractions… • Find the reciprocal of the second fraction. • Multiply the numerators. • Multiply the denominators. • Simplify Let’s Try One… Find the reciprocal of the second fraction. Simplify Multiply the numerators. Multiply the denominators. Let’s Try One… Make the mixed number an improper fraction. Find the reciprocal of the second fraction. Simplify Multiply the numerators. Multiply the denominators. Let’s Try Another… Find the reciprocal of the second fraction. Simplify Multiply the numerators. Multiply the denominators. How do you divide fractions? Now You Try… 3 3 4 1 4 4 1 8 1 5 2 15 2 4 3 5 5 6 10 y 3 y 3 10 …A Few More x x ( 4) 2 8 3b 9b 2 5 5 6 1 4 y y 1 4 10 y 1 n 1 3 4 Dividing Decimals Find 0.65 ÷ 0.25 0.25 )0.65 2 .6 25 )65.0 50 150 –150 0 0.25 has two decimal places so multiple both numbers by 100 to make the divisor an integer. Then divide as a whole number. The answer is reasonable. Evaluating Expression s with Rational Numbers Evaluate the expression for the given value of the variable. 5.25 for n = 0.15 n 5.25 5.25 = n 0.15 0.15 )5.25 35 15 )525 525 0 When n = 0.15, Substitute 0.15 for n. 0.15 has two decimal places, so multiply both numbers by 100 to make the divisor an integer. 5.25 n = 35. 1 A muffin recipe calls for 2 cup of oats. 3 You have 4 cup of oats. How many batches o muffins can you bake using all of the oats you have? The number of batches of muffins you can 1 bake is the number of batches using the oats Understand that you have. List the important the Problem information: 3 The amount of oats is cup. 4 1 One batch of muffins calls for cup of 2 oats. 2 Make a Plan Set up an equation. 3 Solve Let n = number of batches. 3 ÷ 1 =n 4 2 3 • 2 =n 1 4 6 , or 1 1 = n 4 2 You can bake 11 batches of the muffins. 2 4 Look Back 1 One cup of oats would make two batches 2 so 1 is a reasonable answer. Lesson Quiz Divide. 1. 2 5 6 ÷ –1 1 2 –1 8 9 2. –14 ÷ 1.25 3. 3.9 ÷ 0.65 4. Evaluate 112 for x = 6.3. x –11.2 6 17.7 5. A penny weighs 2.5 grams. How many pennies would it take to equal one pound (453.6 grams)? about 182