Shade inequalities and interval notation instantly
Toggle between inequality parsing, a guided interval builder, and interval text input to cover every classroom workflow. The visualizer converts results into both interval and inequality notation and merges overlaps automatically.
Domain controls support negative infinity, fractions, and decimal steps, making it easy to prototype entrance exam questions, SAT-style practice, or lecture slides in seconds.
Number line configuration
Preview
Number line & interval visualizer (inequality shading)
Shade inequalities, unions, and intersections on an SVG number line with step-by-step reasoning and exports.
How it's calculated
Classroom-friendly exports and keyboard shortcuts
Press Enter to regenerate after editing any input, press Ctrl+S for CSV, Ctrl+L to copy the shareable URL, and Ctrl+P to open the print dialog. Share links preserve mode, domain, and interval settings for students.
SVG downloads stay crisp for textbooks and slides, while PNG gives a quick screenshot for LMS uploads. CSV lists every shaded interval and the domain limits for fast documentation.
How to use this number line effectively
Enter a single inequality, a compound statement, or interval notation, then check the shaded result before exporting. Keep the domain and tick spacing visible so students can verify endpoints and open or closed circles.
How it works
The page parses each inequality or interval, normalizes the endpoint rules, and draws the solution on an SVG number line. AND creates an intersection, OR creates a union, and interval notation follows bracket and parenthesis rules. When a coefficient is negative, the inequality direction is flipped during the algebra step shown in the explanation.
When to use
Use this page for classroom checks, worksheet diagrams, and quick verification of inequality notation. It is especially useful when a written answer needs a visual endpoint check before export.
Common mistakes to avoid
- Using an open endpoint for an inclusive inequality, or a closed endpoint for a strict one.
- Mixing AND and OR without checking whether the result should be an intersection or a union.
- Changing the domain limits or tick step so far that important endpoints are hidden.
- Forgetting to flip the inequality sign after multiplying or dividing by a negative number.
Interpretation and worked example
For x < -2 OR x >= 3, the visual should show an open endpoint at -2 with shading left, plus a closed endpoint at 3 with shading right. If the picture does not match the notation, check the connector, endpoint type, and domain before exporting.
See also
Frequently asked questions
How do I enter compound inequalities or mixed unions?
Combine clauses with AND / OR (or the ∪ symbol) in the inequality tab. The solver handles each clause, flips signs when coefficients are negative, and merges overlaps into a clean union.
What export options are available for the number line?
Download SVG for crisp printouts, render a PNG screenshot, export CSV rows with endpoints, copy a shareable URL, or print to PDF directly from the browser.
How are open and closed endpoints shown?
Strict inequalities use open endpoints, while inclusive inequalities use closed endpoints. Interval notation follows the same rule: parentheses are open and brackets are closed.
How do AND and OR change the shading?
Use AND for intersections and OR or the union symbol for unions. The tool parses each part, applies sign changes when needed, and merges overlapping intervals.
What should I check before sharing?
Confirm the domain limits, tick spacing, endpoint type, interval text, and exported format. Small formatting choices can change how students interpret the answer.
Number line input checks
How this visualizer helps
The page turns inequalities and interval notation into visible endpoints, shaded spans, and a short reasoning log. That makes it easier to catch a wrong connector or endpoint before the diagram goes into a worksheet.
Input validation checklist
Before exporting, verify the expression mode, domain minimum and maximum, tick step, endpoint inclusiveness, and AND/OR connector. If a shaded region is missing, widen the domain first so every endpoint is visible.
Teaching workflow
Start with a simple inequality, then add a compound inequality, then compare it with interval notation. Keeping each step visible helps students connect algebraic symbols to the same shaded set.
When to revisit inputs
Revisit inputs when the sign flips, a boundary moves outside the domain, or worksheet formatting requires a different tick interval. The mathematical set may be correct while the printed diagram is hard to read.