Math Problem Statement

|21x - 2| < |7x + 1|

Solution

The inequality in the image is:

21x2<7x+1|21x - 2| < |7x + 1|

To solve this absolute value inequality, we can break it into cases. The general rule is that for any two absolute values A<B|A| < |B|, we need to consider four scenarios:

  1. A<BA < B
  2. A<BA < -B
  3. A<B-A < B
  4. A<B-A < -B

Let's proceed step by step:

Step 1: Break into cases

We'll consider the two main cases:

  1. Case 1: Both expressions are positive or zero. 21x2<7x+121x - 2 < 7x + 1

  2. Case 2: One expression is positive, and the other is negative. 21x2<(7x+1)21x - 2 < -(7x + 1)

We'll solve each case separately and combine the results at the end.

Case 1: 21x2<7x+121x - 2 < 7x + 1

  • Subtract 7x7x from both sides: 21x7x2<121x - 7x - 2 < 1 14x2<114x - 2 < 1

  • Add 2 to both sides: 14x<314x < 3

  • Divide by 14: x<314x < \frac{3}{14}

Case 2: 21x2<(7x+1)21x - 2 < -(7x + 1)

  • Distribute the negative sign: 21x2<7x121x - 2 < -7x - 1

  • Add 7x7x to both sides: 21x+7x2<121x + 7x - 2 < -1 28x2<128x - 2 < -1

  • Add 2 to both sides: 28x<128x < 1

  • Divide by 28: x<128x < \frac{1}{28}

Combine the results:

From Case 1: x<314x < \frac{3}{14}
From Case 2: x<128x < \frac{1}{28}

The stricter inequality is x<128x < \frac{1}{28}.

Thus, the solution is:

x<128x < \frac{1}{28}

Let me know if you need any clarifications or further details.


Here are 5 related questions to expand your understanding:

  1. How do we solve inequalities involving absolute values with different expressions?
  2. Can we graph the solution of 21x2<7x+1|21x - 2| < |7x + 1| on a number line?
  3. How do we handle absolute value equations with equality instead of inequality?
  4. What happens if one or both sides of the inequality are constants instead of expressions?
  5. Can we check the validity of the solution by substituting values back into the inequality?

Tip: Always check for potential extraneous solutions when solving absolute value equations and inequalities by substituting the results back into the original inequality.

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Math Problem Analysis

Mathematical Concepts

Algebra
Absolute Value Inequalities

Formulas

Absolute value inequality cases: |A| < |B| leads to A < B and A < -B

Theorems

Properties of absolute value
Inequality solving techniques

Suitable Grade Level

Grades 9-12