About this calculator
Inequality Calculator is a practical maths tool for students, teachers, spreadsheet users, and anyone checking a calculation quickly. Use it to solve simple linear inequalities and show the result in inequality and interval notation. It is designed to show both the result and the method, so the page is useful for learning, revision, homework checking, and everyday calculations.
Inequality Calculator formula and method
The calculator collects x terms and constant terms on opposite sides, then divides by the x coefficient. If the coefficient is negative, it flips the inequality sign.
- ax + b > c
- x > (c - b) / a when a is positive
- flip the sign when dividing by a negative
How to use the Inequality Calculator
- Enter the main number, expression, equation, or parameters requested by the calculator.
- Check signs, brackets, powers, roots, and decimal points before calculating.
- Review the highlighted result first, then read the supporting working or notes.
- Change one input at a time if you want to compare examples or test your understanding.
- Keep exact values where possible and round only at the final step.
- Use the related calculators when the problem needs a second step, such as rounding or factorisation.
Worked examples
Simple inequality
Input: 2x + 3 > 7
Calculation: 2x > 4, so x > 2.
Result: Solution: x > 2.
Flip sign
Input: -3x + 1 <= 10
Calculation: -3x <= 9. Divide by -3 and flip the sign.
Result: x >= -3.
Open and closed endpoints
Strict inequalities use open endpoints. Less-than-or-equal and greater-than-or-equal use closed endpoints.
Number-line thinking
After finding the boundary, decide whether values greater than or less than the boundary satisfy the original inequality.
Common mistakes to avoid
- Mistake 1
- Do not forget to flip the inequality when dividing by a negative.
- Mistake 2
- Do not treat < and <= as the same.
- Mistake 3
- Always check a test value if unsure which side is shaded.
Edge cases
- Some expressions are undefined, such as division by zero or logarithms of non-positive numbers.
- Different courses may prefer exact radical form, decimal form, interval notation, or a specific rounding rule.
- Very large integer results can become hard to read even when the arithmetic is correct.
- Typed expression parsing supports common notation, but unusual algebra layouts may need rewriting.
Limitations
This calculator is for general educational information only. It follows standard school-level and early college-level maths conventions, but it cannot replace your course instructions, teacher feedback, or specialist software for formal work.
- Check whether your answer should be exact, rounded, simplified, or written in a particular notation.
- Expression and equation parsers are intentionally simple and may not understand every possible layout.
- For high-stakes technical or engineering calculations, verify the result independently.
Frequently asked questions
Can I use decimals?
Yes, most calculators in this batch accept decimal inputs where decimals make sense.
Why does notation matter?
The same mathematical idea can be written in several ways, but calculators need a clear typed format.
Should I round intermediate steps?
Usually no. Keep full precision until the final answer unless instructed otherwise.
Are these calculators suitable for GCSE revision?
Many are useful for GCSE and A-level style practice, especially BODMAS, inequalities, roots, sequences, and simultaneous equations.
What if my answer looks different from a textbook?
It may be equivalent in another form. Check by substituting values or simplifying both forms.
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