Grade 11 · Theory
Quadratic inequalities
Quadratics · about 3 min
Visual overview: Quadratic inequalities1 MIN READ
2 study sections · pause after each one and recall the key ideaA quadratic inequality asks where a parabola is above or below zero, so the answer is a set of intervals.
Key points- Move everything to one side, factorise, and find the critical values (roots).
- Sketch a rough parabola to see where it lies above or below the axis.
- ">" means where the sketch is ABOVE the x-axis; "<" means below.
- Write the answer with correct interval notation and "or" between separate intervals.
- Critical value — a root that separates the intervals.
EXAM TIP
the rough sketch takes ten seconds and turns a guess into a certainty — always draw it.