Lesson 2-6 and 2-7 Multiplying and Dividing Rational Numbers Objective Students will be able to: 1. multiply rational numbers 2. divide rational numbers

Multiplying Rules 1) If the numbers have the same signs then the product is positive. (-7) (-4) = 28 2) If the numbers have different signs then the product is negative. (-7) 4 = -28

Examples 1) (3x)(-8y) 2) Write both numbers as a fraction. Cross-cancel if possible. =-16 Multiplying fractions: top # Bottom # bottom# -24xy

When multiplying two negative numbers, the product is negative. 1. True 2. False Answer Now

When multiplying a negative number and a positive number, use the sign of the larger number. 1. True 2. False Answer Now

3) = =

Multiply: (-3)(4)(-2)(-3) Answer Now

an easy way to determine the sign of the answer 3 negative signs -> Odd -> answer is negative -480 When you have an odd number of negatives, the answer is negative. When you have an even number of negatives, the answer is positive. 4) (-2)(-8)(3)(-10) Do you have an even or odd number of negative signs?

Last one! 5) Positive or negative answer? Positive - even # of negative signs (4) Write all numbers as fractions and multiply. =12

Dividing Rules (same as multiplication) 1) If the numbers have the same signs then the quotient is positive. -32 ÷ (-8 )= 4 2) If the numbers have different signs then the quotient is negative. 81 ÷ (-9) = -9

When dividing two negative numbers, the quotient is positive. 1. True 2. False Answer Now

When dividing a negative number and a positive number, use the sign of the larger number. 1. True 2. False Answer Now

The reciprocal of is where a and b  0. The reciprocal of a number is called its multiplicative inverse. A number multiplied by its reciprocal/multiplicative inverse is ALWAYS equal to 1.

Example #1The reciprocal of is Example #2 The reciprocal of -3 is

Basically, you are flipping the fraction! We will use the multiplicative inverses for dividing fractions.

Which statement is false about reciprocals? 1. Reciprocals are also called additive inverses 2. A number and its reciprocal have same signs 3. If you flip a number, you get the reciprocal 4. The product of a number and its reciprocal is 1 Answer Now

When dividing fractions, change division to multiplying by the reciprocal. Examples 1)

2)

What is the quotient of -21 ÷ -3? Answer Now

Answer Now

Homework: O Lesson 2-6 p. 109, 110 # every 3 rd O Lesson 2-7 p. 115 # every 3rd