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← 1.1 Quadratic Expressions and Equations

Deriving the quadratic formula

Mathematics · Grade 11 · about 40 minutes

Complete the square on ax^2 + bx + c = 0 and arrive at x = [-b plus or minus the square root of (b^2 - 4ac)] divided by 2a.

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  • 8 sections of explanation, worked examples and diagrams
  • 1 practice task with hints and worked answers
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Other lessons in this sub-strand

  1. Perfect-square quadratics
  2. Completing the square
  3. Roots by completing the square
  4. Completing the square when a is not 1
  5. Deriving the quadratic formula
  6. The discriminant
  7. Using the quadratic formula
  8. A line and a quadratic together
  9. Building a quadratic
  10. Quadratics in a story