Transcript Chapter 2 Section 5

Chapter 2 Section 5
Multiplying Integers
Multiplying Two Integers with
Different Signs
• Words: The product of two integers with
different signs.
• Numbers: 3(-2) = -6, -2(3) = -6
Example 1
Find each product.
6(-8)
6(-8) = 6 ∙ -8 =
-48
The factors have
different signs, so the
answer will be
negative.
Example 2
Find each product.
-5(9)
-5(9) = -5 ∙ 9 =
-45
The factors have
different signs, so the
answer will be
negative.
Your Turn
Find each product.
10(-3)
Your Turn
Find each product.
-7(7)
Your Turn
Find each product.
15(-3)
Multiplying Two Integers with the
Same Signs
• Words: The product of two integers with the
same signs is positive.
• Numbers: 3(2) = 6, -2(-3) = 6
Example 3
Find each product.
15(2)
15(2)= 15 ∙ 2 =
30
The factors have the
same signs, so the
answer will be
positive.
Example 4
Find each product.
-5(-6)
-5(-6) = -5 ∙ -6 =
30
The factors have the
same signs, so the
answer will be
positive.
Your Turn
Find each product.
11(9)
Your Turn
Find each product.
-6(-7)
Your Turn
Find each product.
-10(-8)
To find the product of three or more numbers,
multiply the first two numbers. Then multiply
the results by the next number, until you
come to the end.
Example 5
Find each product.
8(-10)(-4)
8(-10) = -80
-80(-4)= 320
Example 5
Find each product.
5(-3)(-2)(-2)
5(-3) = -15
-15(-2)= 30
30(-2)= -60
Your Turn
Find each product.
-2(-3)(4)
Your Turn
Find each product.
6(-2)(3)
Your Turn
Find each product.
(-1)(-5)(-2)(-3)
You can use the rules for multiplying integers
to evaluate algebraic expressions and to
simplify expressions.
Example 7
Evaluate 2xy of x = -4 and y = -2.
2xy = 2(-4)(-2) or 2 ∙ -4 ∙ -2
= -8(-2)
= 16
Example 8
Simplify (2a)(-5b).
(2a) (-5b) = (2)(a)(-5)(b)
= 2 ∙ -5 (a)(b)
= -10ab
Your Turn
Evaluate -5n if n = -7.
Your Turn
Simplify 12(-3z)