NECO 2022 · Paper 1 · Q20

Find the quadratic equation whose roots are 2 and −312-3\frac{1}{2}.

Worked solution (try it first)
  1. The roots give the factors (x−2)(x - 2) and (x+72)\left(x + \frac{7}{2}\right).
  2. Doubling the second gives (2x+7)(2x + 7).
  3. Multiply out: (x−2)(2x+7)=2x2+7x−4x−14(x - 2)(2x + 7) = 2x^2 + 7x - 4x - 14.
  4. So the equation is 2x2+3x−14=02x^2 + 3x - 14 = 0, option D.

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