Page 42 - Algebra 1

L E6S S O N Subtracting Real Numbers
Warm Up
1. Vocabulary The
of a number is the distance from the
3._1 +_4 (SB 3) 3 9
5. _5 - _5 (SB 3) 6 12
(1)
Simplify. 2.86.9-18.94
(SB 2)
4. 41.06 + 83.7 (SB 2)
number to 0 on a number line.
New Concepts Two numbers with the same absolute value but different signs are called opposites. Another name for the opposite of a number is additive inverse. The
sum of a number and its opposite is 0.
Addition and subtraction are inverse operations. Subtracting a number is the same as adding the inverse of the number.
Subtracting Real Numbers
Inverse Property of Addition
For every real number a, a + (-a) = (-a) + a = 0. Example 5 + (-5) = 0
Rules for Subtracting Real Numbers
To subtract a number, add its inverse. Then follow the rules for adding real numbers.
Example 3 - 5 = 3 + (-5) = -2
Example
1
Find each difference.
a. (-12) - 21 SOLUTION
(-12) - 21
(-12) + (-21) = -33
c. 3.2 - (-5.1) SOLUTION
3.2 - (-5.1)
3.2 + (+5.1) = 8.3
b. (-19) - (-8) SOLUTION
(-19) - (-8)
(-19) + (+8) = -11
d. (-_3)- (-_1) 55
SOLUTION
(-_3 )- (-_1 ) 5 5
(-_3)+ (+_1)= -_2 555
Math Reasoning
Analyze What is the meaning of -(-8)?
Online Connection www.SaxonMathResources.com
Lesson 6 27