Page 166 - Math Course 1 (Book 1)

Inequalities: Addition and Subtraction

Mo. 5

Lesson 4

Let’s Begin

KEY CONCEPTS:
1. Solve inequalities by using the Addition
and Subtraction Properties of Inequality. Solve an Inequality Using
Subtraction

MO. 5 - L4a Example
Solving Inequalities: Solve y + 5 > 11.

Addition and Subtraction y + 5 > 11 Write the inequality.

y + 5 – 5 > 11 – 5 Subtract 5 from each side.
Vocabulary A-Z y > 6 Simplify.

Let us learn some vocabulary To check your solution, try any number greater
than 6.
Check

Key Concept y + 5 > 11 Write the inequality.

7 + 5 > 11 Replace y with 7.
Addition and Subtraction 12 > 11
Properties This statement is true.
Words When you add or subtract the same
number from each side of an inequality, Answer The solution is y > 6.
the inequality remains true.

Symbols For all numbers a, b, and c,

1. if a > b, then a + c > b + c Solve an Inequality Using Addition
and a - c > b - c.
Example
2. if a < b, then a + c < b + c
and a - c < b - c.
Solve –21 ≥ d – 8. Check your solution.
Examples 2 < 2 6 > 3
–21 ≥ d – 8 Write the inequality.
2 + 3 < 4 + 3 2 - 4 > 3 - 4
5 < 7 2 > -1 –21 + 8 ≥ d – 8 + 8 Add 8 to each side.

–13 ≥ d Simplify.

The solution is –13 ≥ d or
Answer
d ≤ –13.

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