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Inequalities and linear programming・Form 5 maths

Compound inequalities

A standard method from Inequalities and linear programming: the steps and worked examples.

Steps

  1. Solve each part separately.
  2. Draw both on one number line.
  3. "and": the overlap only. "or": everything covered by either part.

Worked examples

Example 1: Compound inequalities: solve 2x − 1 < 5 and 3 − x ≤ 4.
2x − 1 < 5   →  x < 3
3 − x ≤ 4    →  x ≥ −1
"and":  −1 ≤ x < 3

For the whole topic, read Inequalities and linear programming: key points, common mistakes and how the DSE tests it.

Other methods in this topic