Solve |5x + 3| ≥ 2x + 7: Absolute Value Inequality Analysis

Question

Given:

5x+32x+7 \left|5x + 3\right| \geq 2x + 7

Which of the following statements is necessarily true?

Step-by-Step Solution

Consider the inequality: 5x+32x+7 \left|5x + 3\right| \geq 2x + 7 .

This inequality divides into two cases:

(1) 5x+32x+7 5x + 3 \geq 2x + 7 and (2) 5x+3(2x+7) 5x + 3 \leq -(2x + 7) .

For inequality (1):

5x+32x+7 5x + 3 \geq 2x + 7

Subtract 2x 2x from both sides:

3x+37 3x + 3 \geq 7

Subtract 3 from both sides:

3x4 3x \geq 4

Divide both sides by 3:

x43 x \geq \frac{4}{3}

For inequality (2):

5x+32x7 5x + 3 \leq -2x - 7

Add 2x 2x to both sides:

7x+37 7x + 3 \leq -7

Subtract 3 from both sides:

7x10 7x \leq -10

Divide both sides by 7:

x107 x \leq -\frac{10}{7}

The solution sets are x43 x \geq \frac{4}{3} and x107 x \leq -\frac{10}{7} .

Answer

x43 x \geq \frac{4}{3} and x107 x \leq -\frac{10}{7}