MEPX
Chapter 5 of 10All chapters
  1. 1Why letters
  2. 2Rearranging
  3. 3Expanding and factorising
  4. 4Straight lines
  5. 5Quadratics
  6. 6Fractions and powers
  7. 7Two unknowns
  8. 8Inequalities
  9. 9Functions
  10. 10Turning words into algebra

Chapter 5 of 10

Quadratics

When the unknown is squared.

Three routes

Factorise when it is tidy, complete the square when you need the vertex, or use the formula when nothing else works. All three give the same answers.

  • A quadratic graphs as a parabola, opening up when the squared term is positive.
  • The discriminant tells you whether there are two solutions, one or none.

Why they appear

Anything involving area, projectile motion or a product of two changing quantities produces a squared term. That is why this one shape is worth knowing well.