Solve Inequality Interval Notation Calculator

Analyze inequality steps, interval notation, and boundary rules. Review tables, plots, and downloadable results quickly. Learn solution sets with clear examples and guidance today.

Calculator

Supported input forms:
Simple: ax + b < c, ax + b ≤ c, ax + b > c, or ax + b ≥ c
Compound: lower < ax + b < upper and related inclusive forms

Example Data Table

Inequality Solved Form Interval Notation
2x + 3 < 11 x < 4 (-∞, 4)
-3x + 6 ≥ 0 x ≤ 2 (-∞, 2]
1 ≤ 2x - 1 < 7 1 ≤ x < 4 [1, 4)
5x - 10 > 15 x > 5 (5, ∞)
4 ≤ x + 2 ≤ 8 2 ≤ x ≤ 6 [2, 6]

Formula Used

For a linear inequality of the form ax + b ? c, isolate x using the same algebra steps used for equations.

Subtract b from both sides first.

Then divide both sides by a.

If a is negative, reverse the inequality sign after division.

General form:

ax + b ? c

ax ? c - b

x ? (c - b) / a

When solving a compound inequality, solve both sides separately and intersect the two solution sets.

Interval notation uses parentheses for excluded endpoints and brackets for included endpoints.

How to Use This Calculator

  1. Select the inequality mode you want to solve.
  2. Enter values for a and b in the expression ax + b.
  3. For simple mode, choose the operator and enter c.
  4. For compound mode, enter both bounds and both comparison signs.
  5. Press Solve Inequality to generate the answer.
  6. Read the solved form, interval notation, set builder form, and worked steps.
  7. Use the graph to inspect the solution region visually.
  8. Download the result as CSV or print it as PDF when needed.

About Solving Inequalities and Interval Notation

Solving inequalities is a core skill in algebra, pre calculus, and many applied maths topics. Unlike equations, inequalities describe ranges of values rather than a single answer. That makes interval notation useful because it compresses the final solution into a compact, standard format that teachers, students, and software tools all recognize.

A typical linear inequality starts with an expression such as ax + b on one side and a constant or another simple value on the other. The goal is to isolate x using algebraic operations. You can add, subtract, multiply, or divide both sides, but one rule matters most: if you divide or multiply by a negative number, the inequality direction must reverse. Many mistakes happen at this step.

Interval notation then converts the solution into endpoint based form. Parentheses mean the endpoint is not included. Brackets mean the endpoint is included. For example, x < 4 becomes (-∞, 4), while x ≤ 4 becomes (-∞, 4]. A bounded solution such as 2 ≤ x < 7 becomes [2, 7). If no values satisfy the inequality, the solution is the empty set, written as ∅.

Compound inequalities combine two comparisons at once. These often appear in the form a < bx + c ≤ d. To solve them, isolate the variable across all parts or solve each side separately and intersect the results. The final answer often becomes a closed, open, or half open interval.

This calculator helps reduce sign errors, shows interval notation clearly, and gives a quick graph view of the solution set. It is useful for homework checking, classroom demonstrations, and practice with inequality transformations.

FAQs

1. What is interval notation?

Interval notation is a compact way to show all values that satisfy an inequality. It uses parentheses for excluded endpoints and brackets for included endpoints.

2. When do I reverse the inequality sign?

You reverse the sign only when multiplying or dividing both sides by a negative number. This keeps the comparison mathematically correct.

3. What does a bracket mean in interval notation?

A bracket means the endpoint is included in the solution set. It matches ≤ or ≥ in the solved inequality.

4. What does a parenthesis mean in interval notation?

A parenthesis means the endpoint is not included. It matches < or > in the solved inequality.

5. Can this calculator solve compound inequalities?

Yes. Use compound mode to enter a lower bound, an expression, and an upper bound. The calculator solves both sides and intersects them.

6. What happens if no number satisfies the inequality?

The result is the empty set, written as ∅. This means the inequality has no valid solution values.

7. What does all real numbers mean?

It means every real number satisfies the inequality. In interval notation, this appears as (-∞, ∞).

8. Why is graphing useful for inequalities?

Graphing helps you see endpoint inclusion and the direction of the solution set. It also makes interval answers easier to verify quickly.

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