7th Grade Math

Lesson 2B Add and Subtract Integers 89

Add Integers with the Same Sign

Find - 26 + (-17).

• 26 + (-17) = - 43 Both integers are negative, so the sum is negative.

c. - 14 + (-16) d. 23 + 38

The integers 5 and -5 are called opposites because they are the same

distance from 0, but on opposite sides of 0. Two integers that are

opposites are also called additive inverses.

Additive Inverse Property

Words The sum of any number and its additive inverse is 0.

Example 5 + (-5) = 0

When you add integers with different signs, start at zero. Move right

for positive integers. Move left for negative integers.

Add Integers with Different Signs

Find 5 + (-3). Find - 3 + 2.

0 1 2 3 4 5

• 3
  5
  -^3 -^2 -^10

+ 2

• 3

So, 5 + (-3)^ = 2. So, - 3 + 2 = - 1.

e. 6 + (-7) f. - 15 + 19

Add Integers with Different Signs

Words To add integers with different signs, subtract their absolute

values. The sum is:

• positive if the positive integer’s absolute value is greater.


• negative if the negative integer’s absolute value is greater.

Examples 9 + (-4) = 5 - 9 + 4 = - 5

Everyday Use

Opposite something that

is across from or is facing

the other way, as in

running the opposite way

Math Use

Opposite two numbers

that are the same distance

from 0 on a number line

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