Solving Multi-Step Inequalities

Introduction

Multi-step inequalities extend the ideas from one-step inequalities by adding layers: combining like terms, distributing, and sometimes dealing with negative coefficients.
Because inequalities describe ranges of solutions rather than single values, each step must preserve the direction of the inequality — except when multiplying or dividing by a negative number, which flips the inequality sign.

This article assumes you already understand:

What Are Multi-Step Inequalities?

A multi-step inequality is any inequality that requires more than one algebraic operation to isolate the variable.

Examples:

Typical steps include:

Key Idea: Flipping the Inequality

When solving inequalities, the only time the inequality sign flips is when you:

Examples:

This rule is essential for solving inequalities with negative coefficients.

General Strategy for Solving Multi-Step Inequalities

Worked Examples

Example 1

Solve: $$3x - 5 \ge 7$$ Steps:

Example 2

Solve: $$4 - 2(x + 1) < 6$$ Steps:

Example 3

Solve: $$5x + 8 \le 3x - 4$$ Steps:

Calculator

Solving inequalities

  • As with one-step inequalities, multi-step inequalities can be solved via the $\operatorname{solveLinearInequality}()$ function
  • Note that the inequality must be wrapped in quotes to stop the calculator evaluating it first
solveLinearInequality('3 - 2(x - 4) <= 11') solveLinearInequality('7 - (x + 2) > 3x')

Exercises

  1. Solve the inequality: $4x - 7 > 9$

    Solution

    $4x - 7 > 9$
    Add $7$: $4x > 16$
    Divide by $4$:
    $x > 4$
  2. Solve: $3 - 2(x - 4) \le 11$

    Solution

    $3 - 2(x - 4) \le 11$
    Distribute: $3 - 2x + 8 \le 11$
    Combine: $11 - 2x \le 11$
    Subtract $11$: $-2x \le 0$
    Divide by $-2$ (flip sign):
    $x \ge 0$
  3. Solve: $5x + 12 \ge 2x - 6$

    Solution

    $5x + 12 \ge 2x - 6$
    Subtract $2x$: $3x + 12 \ge -6$
    Subtract $12$: $3x \ge -18$
    Divide by $3$:
    $x \ge -6$
  4. Solve the inequality with a negative coefficient: $-3x + 5 < 2$

    Solution

    $-3x + 5 < 2$
    Subtract $5$: $-3x < -3$
    Divide by $-3$ (flip sign):
    $x > 1$
  5. Solve: $7 - (x + 2) > 3x$

    Solution

    $7 - (x + 2) > 3x$
    Distribute: $7 - x - 2 > 3x$
    Combine: $5 - x > 3x$
    Add $x$: $5 > 4x$
    Divide by $4$:
    $x < \frac{5}{4}$
  6. Solve: $-4(2x - 1) \ge 12$

    Solution

    $-4(2x - 1) \ge 12$
    Distribute: $-8x + 4 \ge 12$
    Subtract $4$: $-8x \ge 8$
    Divide by $-8$ (flip sign):
    $x \le -1$
  7. Solve: $2x + 3 < 5x - 9$

    Solution

    $2x + 3 < 5x - 9$
    Subtract $2x$: $3 < 3x - 9$
    Add $9$: $12 < 3x$
    Divide by $3$:
    $4 < x$ or $x > 4$
  8. Solve the inequality and remember to flip the sign: $-5(x - 2) \le 15$

    Solution

    $-5(x - 2) \le 15$
    Distribute: $-5x + 10 \le 15$
    Subtract $10$: $-5x \le 5$
    Divide by $-5$ (flip sign):
    $x \ge -1$