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NECO 2024 · Paper 1 · Q20

If f(x)=3x2−9x−5f(x) = 3x^2 - 9x - 5, find f(−3)f(-3).

Worked solution (try it first)
  1. Put x=−3x = -3 into f(x)=3x2−9x−5f(x) = 3x^2 - 9x - 5.
  2. (−3)2=9(-3)^2 = 9, so 3x2=273x^2 = 27.
  3. And −9×(−3)=+27-9 \times (-3) = +27.
  4. So f(−3)=27+27−5=49f(-3) = 27 + 27 - 5 = 49, option D.

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