Question

    If 27 (x+y)³ − 8(x−y)³ = (x + 5y)

    (Ax² + By² + Cxy), then what is the value of (A+B-C)?
    A 18 Correct Answer Incorrect Answer
    B 16 Correct Answer Incorrect Answer
    C 13 Correct Answer Incorrect Answer
    D 11 Correct Answer Incorrect Answer

    Solution

    27 (x + y)3 – 8 (x – y)3 = (x + 5y (Ax2 + By2 + cxy) Value of (A + B – C) = ? So, put x = 1, y = -1 = 27[1 – 1]3 – 8[1 – (- 1)]3 = [1 + 5 × - 1][A + B – C] + 64 = + 4[ A + B - C = A + B – C = 16

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