Inequality Calculator
Solve linear and quadratic inequalities with interval notation and a graph.
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How to use this calculator
Type an inequality such as 2x + 3 ≤ 11 or x² − 5x + 6 > 0. The calculator solves it and shows the answer in inequality form and interval notation, with a graph.
How it's calculated
Solve like an equation, but flip the sign when you multiply or divide by a negative number. For quadratics, find where the expression equals 0, then test each region between those values.
Worked example
−3x > 12: divide by −3 and flip the sign, so x < −4. In interval notation that is (−∞, −4).
Frequently asked questions
Why does the sign flip?
Multiplying or dividing by a negative reverses the order of numbers, so 2 < 3 becomes −2 > −3.
What do the brackets mean?
A round bracket leaves the end number out. A square bracket includes it.
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Last updated October 2026. Results are for learning and guidance; always check important work. Calculations run in your browser and are not stored.