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Multiplying Integers
Multiplying Integers• Let’s model integer multiplication:
2 • -3= -6 -6 • 5 = -30
Multiplying Integers
So, a positive number times a negative number is a ________ number.
Negative
And, a negative number times a positive number is a ________ number.
Negative
What is the answer to a negative times a negative?
Multiplying Integers
• Look at the pattern:-2 • 3 = -6-2 • 2 = -4-2 • 1 = -2-2 • 0 = 0-2 • -1 = ??
What is happening to the product each time?It is increasing by 2
-2 • -1 = 0 + 2 which is 2
Multiplying Integers
A negative number times a negative number is a ________ number
Positive
Multiplying Integers
Here is a way to remember it:
Good guys are +, Bad guys are –
Coming into town is +, Leaving Town is –
Good is +, Bad is -If a good guy (+) comes into town (+), that’s good (+)
If a good guy (+) leaves town (-), that’s bad (-)
If a bad guy (-) comes into town (+), that’s bad (-)
If a bad guy (-) leaves town (-), that’s good (+)
Multiplying Integers
• Multiply:4(-3)-12
-2 • -918
(-25)(6)-150
-7 • -32224
12(10)120
-16(-5)80
The Integer Song
Verse 4Here is a rule that you must know
when multiplying integers,If signs are the sameIf signs are the sameIf signs are the same
The answer’s always positive.
The Integer Song
Verse 5Another rule that you must know when
multiplying integers,If signs are differentIf signs are differentIf signs are different
The answer’s always negative.
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