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2.3
Multiply and Divide Integers
Review
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-12+8
0-(-9)
-7+(-4)
2-(-4)
-6-(-9)-(4)+13
Write the sum of y and negative five
True, sometimes true or false:
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The difference between a number and
its additive inverse is zero
The sum of a negative number and a
negative number is a negative number
Multiplying
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Steps for Multiplying Integers
1. Multiply the numbers and ignore
their signs
2. If both have the same signs
(positive-positive or negativenegative) then the answer is a
positive number.
3. If they opposite signs (one
negative and one positive) then the
answer is negative.
Examples
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-7(4) = -28
3(-2) = -6
4(5) = 20
(-6)(-1) = 6
Properties
Multiplicative property of zero
A*0 = 0
Multiplicative property of one
a*1 = a
Commutative property
a*b = b*a
2*3 = 3*2
Associative Property of Multiplication
(a*b)*c = a*(b*c)
Division
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Same rules as multiplication
1. Divide the numbers and ignore
their signs
2. If both have the same signs
(positive-positive or negativenegative) then the answer is a
positive number.
3. If they opposite signs (one
negative and one positive) then the
answer is negative.
Properties
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Top = numerator
Bottom = denominator
a/1=a
0/a=0
Zero cannot be in the denominator
a/0 = undefined
b/a is okay as long as a does not
equal 0
examples
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-2 / -2 = 1
50 / -10 = 5
Try it
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(-38)(51)
-1938
-7(-8)(9)(-2)
-1008
Is -3 a solution to 12 = -4a
Yes’m
What is zero divided by -17
Zero
84/-6
-14
Is -3 a solution to: -6/y = -2
No!
The daily high temperatures for one week in
winter were:
-7, -8, 0, -1, -6, -11, -2
-5
2.3 homework
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1 thru 119 EOO
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20, 36, 48, 60, 80, 84, 90, 100,
108, 112