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WAEC 2020 · Paper 1 · Q9

If x=3x = 3 and y=−1y = -1, evaluate 2(x2−y3)2(x^2 - y^3).

Worked solution (try it first)
  1. x2=32=9x^2 = 3^2 = 9 and y3=(−1)3=−1y^3 = (-1)^3 = -1.
  2. Inside the bracket: 9−(−1)=109 - (-1) = 10.
  3. So 2(x2−y3)=2×10=202(x^2 - y^3) = 2 \times 10 = 20, option C.

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