Grade 8, Vol 2 Math Student Handbook

Where Math Gets Real

Solving Inequalities An inequality compares quantities. Instead of an equal sign, inequalities are indicated by the symbols >, <, ≤ or ≥. Sometimes variables in inequalities have coefficients or are paired with another number. These inequalities require addition, subtraction, multiplication, or division to solve. You can use inverse operations to isolate and solve for the variable.

INEQUALITY

OPERATION

INVERSE OPERATION ISOLATING THE VARIABLE SOLUTION

b + 7 > 2 – 7 – 7

b + 7 > 2

addition

subtraction

b > -5

k – 6.2 ≤ 5.01 + 6.2 + 6.2

k – 6.2 ≤ 5.01

subtraction

addition

k ≤ 11.21

21 p 21

84 21

p ≥ 4

21 p ≥ 84

multiplication

division

m ÷ 2.5 < -12 × 2.5 × 2.5

m ÷ 2.5 < -12

division

multiplication

m < -30

NOTE: If you have to multiply or divide by a negative number in order to isolate the variable, you will need to switch the direction of the sign.

less than

reater than or equal to

-4.25 s -4.25

14.45 -4.25

y ÷ -9 ≥ -6 × -9 × -9 y ≤ 54

< s > -3.4

reater than

less than or equal to

YOUR TURN ✎

4. g ÷ 7.2 > 8.5

1. h ÷ 24 ≤ 6

5. 126 ≥ -12 n

2. q + 7.3 > -13.2

6. 13.3 – z < 30

3. 2.4 d ≥ 23.4

These Drones Save Lives! > INVERSE OPERATIONS

Sessions 23 & 24 71

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