Warm Up

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Preview
Warm Up
California Standards
Lesson Presentation
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Warm Up Multiply or divide. 1. 6(7)

42
3. 42 7
6
4.
2.
4
5. Write as a mixed number.
6.
Write as an improper fraction.
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Vocabulary
reciprocal multiplicative inverse
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When you multiply or divide two numbers, the
signs of the numbers determine whether the result
is positive or negative.




Numbers
Product/Quotient
Both positive
Positive
Negative
One negative
Both negative
Positive
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Additional Example 1 Multiplying and Dividing
Signed Numbers
Find the value of each expression.
A.
The product of two numbers with different
signs is negative.
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B.
The quotient of two numbers with the same
sign is positive.
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Additional Example 1 Multiplying and Dividing
Signed Numbers
Find the value of each expression.
C.
Multiply.
The quotient of two numbers with different
signs is negative.
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Check It Out! Example 1
Find the value of each expression.
1a. 35 ? (5)
The quotient of two numbers with different
signs is negative.
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1b. 11(4)
The product of two numbers with the same
sign is positive.
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1c. 6(7)
The product of two numbers with different signs
is negative.
42
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Two numbers are reciprocals if their product is
1. A number and its reciprocal are called
multiplicative inverses.
To divide by a number, you can multiply by its
multiplicative inverse.
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Additional Example 2A Dividing with Fractions
Example 2 Dividing by Fractions
Divide.
To divide by , multiply by .
Multiply the numerators and multiply the
denominators.
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Additional Example 2B Dividing with Fractions
Divide.
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Check It Out! Example 2a
Divide.
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Check It Out! Example 2b
Divide.
Multiply the numerators and multiply the
denominators.
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Check It Out! Example 2c
Divide.
The signs are different, so the quotient is
negative.
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The number 0 has special properties for
multiplication and division.
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Additional Example 3 Multiplying and Dividing
with Zero
Multiply or divide if possible.
0
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A.
Zero is divided by a nonzero number.
The quotient of zero and any nonzero number
is 0.
0
B. 22 ? 0
A number is divided by zero.
undefined
Division by zero is undefined.
C. 8.45(0)
A number is multiplied by zero.
0
The product of any number and 0 is 0.
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Check It Out! Example 3
Multiply or divide.
3a.
Zero is divided by a nonzero number.
The quotient of zero and any nonzero number
is 0.
0
3b. 0 0
A number is divided by zero.
undefined
A number divided by 0 is undefined.
3c. (12.350)(0)
A number is multiplied by zero.
The product of any number and 0 is 0.
0
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Additional Example 4 Recreation Application
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Additional Example 4 Continued
Multiply the numerators and multiply the
denominators.
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The hot-air balloon lands 5 miles from the
liftoff site.
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Check It Out! Example 4
What if? On another hot-air balloon trip, the
wind speed is 5.25 mi/h. The trip is planned for
1.5 hours. The balloon travels in a straight line
parallel to the ground. How many miles away from
the liftoff site will the balloon land?
5.25(1.5)
Rate times time equals distance.
Distance traveled.
7.875 mi
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Lesson Quiz
Find the value of each expression.
35 7
1.
2. 2(6)
5
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Multiply or divide if possible.
0
undefined
15 miles