Inequality Calculator

Form: a·x + b ? c. Division by a negative flips the inequality.

Solution (set-builder)
Interval notation
Status

Inequality Calculator – Free Online Inequality Solver

Our free Inequality Calculator helps you solve and graph inequalities step-by-step. Enter any linear inequality (like 2x + 5 > 7) or a compound inequality (like -3 ≤ 2x + 1 < 7) and get the solution in:

  • Set-builder notation

  • Interval notation

  • Number line graph

  • ✅ Step-by-step explanation of each algebraic operation

What Is an Inequality?

An inequality compares two values or expressions using symbols:

< (less than)

≤ (less than or equal to)

> (greater than)

≥ (greater than or equal to)

For example, 2x + 1 ≥ 5 means “two times x plus one is greater than or equal to five.” The solution is the set of all x values that make the statement true.

How to Use the Inequality Solver

  1. Choose mode: single inequality (ax + b ? c) or compound inequality (L ? kx + m ? R).
  2. Enter coefficients and constants.
  3. Pick inequality signs (<, ≤, >, ≥).
  4. Click Solve.
  5. View the result as:
    • Set-builder notation { x > 3 }
    • Interval notation (3, ∞)
    • Number line visualization

Solving Inequalities – Step by Step

The calculator applies standard rules:

  • Adding/subtracting the same value from both sides keeps the inequality the same.

  • Multiplying/dividing by a positive number keeps the sign the same.

  • Multiplying/dividing by a negative number flips the inequality sign.

Example:
-2x + 4 ≤ 10
→ Subtract 4 → -2x ≤ 6
→ Divide by -2 (flip sign) → x ≥ -3

Example Calculations

  • Single Inequality:
    Solve 2x + 1 < 5 → Subtract 1 → 2x < 4 → Divide by 2 → x < 2
    Interval: (-∞, 2)

  • Compound Inequality:
    Solve -3 ≤ 2x + 1 < 7
    Break into two parts:
    -3 ≤ 2x + 1 and 2x + 1 < 7
    x ≥ -2 and x < 3
    Interval: [-2, 3)

Types of Inequalities Supported

  • Linear inequalities in one variable (ax + b ? c)

  • Compound inequalities (L ? ax + b ? R)

  • Strict inequalities (<, >)

  • Inclusive inequalities (≤, ≥)

  • Graphical solution on a number line

FAQ – Inequality Solver

Q: Can this tool solve compound inequalities?
Yes ✅ — it handles inequalities with two bounds, like -3 ≤ 2x + 1 < 7.

Q: Does the calculator flip the inequality when dividing by a negative?
Yes — the solver automatically flips < to > (and vice versa) when dividing by a negative number.

Q: What notations are supported?

  • Set-builder form { x ≥ 4 }

  • Interval notation [4, ∞)

  • Graphical solution on a number line

Q: Can I graph inequalities?
Yes — the solution is plotted on a number line, showing open or closed endpoints.

Q: Does it handle quadratic inequalities?
This version is for linear and compound inequalities. For quadratic or higher, use a quadratic inequality solver.

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