Linear inequalities (exam drills)

Solve inequalities with brackets and negative coefficients; represent solutions on a number line.

Key formulas

Flip the sign when×or÷byanegative\text{Flip the sign when} \times or \div by a negative
Open circle for<or>\text{Open circle for} < or >
Closed circle for≤or≥\text{Closed circle for} \le or \ge

Same algebra, careful signs

Expand brackets, collect terms, isolate x. The only extra rule: multiplying or dividing by a negative reverses the inequality.

Number-line answers

Many papers award a mark for a correct diagram. Use an open circle for strict inequalities and shade the correct ray.

Integer solutions

If the question asks for the largest integer x satisfying x < 3.2, the answer is 3 — inequality solutions are often more than a single value.

Exam habit

Highlight every division by a negative in red (or with a star) so the flip is never missed.

Worked example

Negative coefficient

Problem. Solve −5x ≤ 20.

Solution. Divide by −5 and flip: x ≥ −4.

Review quiz

1 / 4

−5x ≤ 20 ⇒

Practice questions

  1. Solve 3(x − 2) > 2x + 5 and show on a number line.
  2. Solve −5x ≤ 20.
  3. Solve 7 − 4x ≥ 15.
  4. Find the largest integer x such that 2x − 1 < 10.

Study notes

Do I flip when moving terms across?

No — adding/subtracting the same amount never flips. Only ×/÷ by a negative flips.

Is x = 4 allowed for x ≥ 4?

Yes — closed circle.

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