Solving quadratics by factorising

Turn x² - 5x + 6 = 0 into two brackets and read off both answers. About 9 minutes, GCSE.

What you will do

  1. What is a quadratic?. A quadratic has an x² term, like x² - 5x + 6 = 0. It usually has two solutions.
  2. Factorise, then solve. We look for two numbers that multiply to the last number (6) and add to the middle one (-5). Then each bracket can be set to zero.
  3. The zero product rule. If two things multiply to give 0, one of them must be 0. That is why (x - 2)(x - 3) = 0 gives x = 2 or x = 3.
  4. A harder one. When the x² has a number in front, the same idea works - just take more care.
  5. Your turn. Find both solutions.

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