Page 72 - Algebra 1
P. 72
To multiply signed numbers, use the rules in the table below.
Multiplying Signed Numbers
The product of two numbers with the same sign is a positive number. Examples (3)(4) = 12 (-5)(-3) = 15
The product of two numbers with opposite signs is a negative number. Examples (-2)(4) = -8 6(-2) = -12
Multiplying Rational Numbers
Simplify each expression. Justify your answer. a. 4(-8)
Example
1
SOLUTION
4(-8) = -32
b. (-6)(-0.7) SOLUTION (-6)(-0.7) = 4.2
The product of two numbers with opposite signs is negative.
The product of two numbers with the same sign is positive.
To raise a number to a power, use repeated multiplication to simplify.
Raising a Number to a Power
Example
2
Simplify each expression. a. (-3)4
SOLUTION
(-3)4
= (-3)(-3)(-3)(-3) = 81
b. (-3)3
SOLUTION
(-3)3
= (-3)(-3)(-3) = -27
c. -34
SOLUTION
-34
= -1 ยท 34
= -1[(3)(3)(3)(3)] = -1(81)
= -81
Use repeated multiplication.
Use repeated multiplication.
Use repeated multiplication.
Find the product inside the brackets. Multiplication Property of -1
Math Reasoning
Generalize How does an even or odd exponent affect the product of
the power of a negative number?
Lesson 11 57
