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JAMB 1993 · UME · Q17

If the function ff is defined by f(x+2)=2x2+7x−5f(x + 2) = 2x^2 + 7x - 5, find f(−1)f(-1).

Worked solution (try it first)
  1. f(−1)f(-1) needs x+2=−1x + 2 = -1, so x=−3x = -3.
  2. Substitute: 2(−3)2+7(−3)−5=18−21−52(-3)^2 + 7(-3) - 5 = 18 - 21 - 5.
  3. So f(−1)=−8f(-1) = -8, option B.

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