Algebra 1 Foundational

Compound Inequalities

Solve AND and OR compound inequalities — find the intersection or union of two solution sets, graph on a number line, and write in interval notation.

Live Calculator · Step-by-Step · Algebra 1
Input
Three-part inequality: left ≤ ax + b ≤ right
−3 ≤ 2x + 1 ≤ 7
Examples
Inequality 1
— OR —
Inequality 2
x < −2  OR  x ≥ 5
Examples
Solution
Enter values and click Solve to see the solution.
Step-by-Step Solution
Number Line
AND → Intersection
a ≤ x < b   →   [a, b)

AND means both conditions must be true simultaneously. You solve the three-part inequality by applying the same operations to all three parts at once.

The result is the intersection of both solution sets — typically a bounded interval between two values.

Special case: if the left bound ends up greater than the right bound after solving, the answer is No Solution (∅).

Flip all inequality signs when you multiply or divide every part by a negative number.
OR → Union
x < a OR x ≥ b   →   (−∞, a) ∪ [b, +∞)

OR means at least one condition is true. Solve each inequality independently, then take the union of both solution sets.

The graph typically shows two separate shaded regions, each extending to ±∞ on one side.

Special case: if the two regions overlap or touch, the solution is All Real Numbers (−∞, +∞).

No Solution is impossible with OR — at least one region always has values. All Real Numbers is possible when the regions cover the whole line.

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