Chapter 7 Lesson 4 Solving Inequalities by Adding or
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Transcript Chapter 7 Lesson 4 Solving Inequalities by Adding or
Chapter 7 Lesson 4
Solving Inequalities by
Adding or Subtracting
pgs. 345-349
What you’ll learn:
Solve inequalities by using the
Addition or Subtraction
Properties of Inequality
Solving an inequality means finding
values for the variable that make the
inequality true.
You can solve inequalities by using the
Addition and Subtraction Properties of
Inequalities (pg. 345) This is the same
concept as using the
Addition/Subtraction Properties of
Equations (Lesson 3-3 pgs. 110-111)
Example 1: Solving an Inequality
using Subtraction
Solve -13 9 + b
Write the inequality:
Check your solution
-13 9 + b
Subtract 9 from each side: -13 9 + b
-9 -9
Simplify: -22 b or b -22
To check your solution, try any number less than or equal
to -22
Check using -20:
Check:
using
-30
Check using -22:
-13 9 + -20
-13 9 + -30
-13 9 + (-22)
-13 -11
-13
-21
-13 -13
Example 2: Solving an Inequality
using Addition
Solve a - 5 6
Check your solution
Write the inequality: a - 5 6
Add 5 to both sides: a - 5 6
+5 +5
Simplify: a 11
Check your result by using any number greater than 11
Check using 12:
12 - 5 6
76
Check using 32:
32 - 5 6
27 6
Check using 7:
7-56
26
Example 3: Graph Solutions of
Inequalities
Solve h + 4 4 Then graph the
solution on a number line.
Write the inequality: h + 4 4
Subtract 4 from each side: h + 4 0
- 4 -4
h0
The solution is h 0
Check: any number greater than 0
I’m using 1
1+44
54
Now graph the solution
On a number line.
Done on board in class.
Example 4: Use an Inequality to
Solve a Problem
Chris is saving money for a ski trip. He has
$62.50, but his goal is to save at least
$100. What is the least amount Chris
needs to save to reach his goal?
Explore: We need to find the least amount Chris needs to save
Plan: Let x represent the amount he needs to save. Write
an inequality to represent the problem. Remember
at least means greater than or equal to.
x + 62.50 100
Solve: x + 62.50 100
- 62.50 -62.50
x 37.50
So the least amount that Chris
needs to save is $37.50
Your Turn! Solve the inequality,
graph your solution, do a check
A. c - (-2) 3
B.
c+23
-2 -2
c1
Check using -1
-1 - (-2) 3
13
25 n + (-12)
+12
25 n + (-12) +12
37 < n , n 37
Check using 40
25 40 + (-12)
25 28
g - 5 + 5 13 + 5
Check using 4
3
6
3 3 6
3
4 - 12 2 1
3
6
g3 5
1
1
6
2 2
6
k + 9 -21 Check using -25 3
D. k + 9 -21
- 9 -9
-25 + 9 -30
k -30
-16 -30
C. g - 1 2 2 1
Extra Practice by the door on your
way out. See me if you have
questions/problems!