Math Problem Statement

simple absolute value inequalities

Solution

Absolute value inequalities involve expressions with absolute values that are set in inequality form. Solving these requires understanding how absolute values work and breaking down the inequality into different cases. Here’s a basic guide:

1. Basic Principle of Absolute Value Inequalities

For an expression xa|x| \leq a or xa|x| \geq a, we handle it as follows:

  1. If xa|x| \leq a:
    This means axa-a \leq x \leq a.
    Example: x5|x| \leq 5 implies 5x5-5 \leq x \leq 5.

  2. If xa|x| \geq a:
    This means xax \leq -a or xax \geq a.
    Example: x3|x| \geq 3 implies x3x \leq -3 or x3x \geq 3.

2. Solving Steps for Simple Absolute Value Inequalities

  1. Isolate the absolute value expression if it’s not alone.
  2. Determine if the inequality is of the form \leq (and type) or \geq (or type).
  3. Write the compound inequality according to the rules above.
  4. Solve each part of the inequality separately.

Examples:

  1. Example 1: Solve x+2<4|x + 2| < 4
    Since x+2<4|x + 2| < 4 (and type inequality): 4<x+2<4-4 < x + 2 < 4 Solve by isolating xx: 42<x<42-4 - 2 < x < 4 - 2 6<x<2-6 < x < 2 Solution: 6<x<2-6 < x < 2.

  2. Example 2: Solve 3x15|3x - 1| \geq 5
    Since 3x15|3x - 1| \geq 5 (or type inequality): 3x15or3x153x - 1 \leq -5 \quad \text{or} \quad 3x - 1 \geq 5 Solve each inequality:

    • For 3x153x - 1 \leq -5: 3x43x \leq -4 x43x \leq -\frac{4}{3}
    • For 3x153x - 1 \geq 5: 3x63x \geq 6 x2x \geq 2 Solution: x43x \leq -\frac{4}{3} or x2x \geq 2.

Would you like further details or have questions?

Related Questions

  1. How do we handle inequalities when the inequality sign flips during the solving process?
  2. How can we solve absolute value inequalities with quadratic expressions inside?
  3. What are practical applications of absolute value inequalities?
  4. How do compound inequalities differ from absolute value inequalities?
  5. What happens if an absolute value inequality has no solution?

Tip:

Always remember to interpret absolute value inequalities as either "and" or "or" types, depending on whether they are \leq or \geq inequalities.

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Math Problem Analysis

Mathematical Concepts

Absolute Value
Inequalities
Algebra

Formulas

|x| ≤ a implies -a ≤ x ≤ a
|x| ≥ a implies x ≤ -a or x ≥ a

Theorems

Absolute Value Inequality Theorem

Suitable Grade Level

Grades 8-10