Download Lesson 2-2 - Elgin Local Schools

Lesson 2-2
Adding and Subtracting Rational
Numbers
Use a number line to find each sum.
8 + (-5)
-1 + (-4)
Definition
• Addition of Rational Numbers– To add rational numbers with the same
sign, add their absolute values. The sum
has the same sign as the addends.
– To add rational numbers with different
signs, subtract the lesser absolute value
from the greater absolute value. The sum
has the same sign as the number with the
greater absolute value.
Find each sum.
6 + (-14)
3
2
  ( )
7
7
Definitions
• Opposites- Every positive rational number can
be paired with a negative rational number,
called its opposite. (5 and -5)
• Additive Inverse- A number and its opposite.
• Additive Inverse Property- The sum of a
number and its additive inverse is zero.
• Subtraction of Rational Numbers- To subtract
a rational number, add its additive inverse.
Find each difference.
12.7 – (-18.4)
18 - 23
2 3
 
9 10