Question

    If 4x + 1/3x = 12 then find the value of 9x2

    +1/16x2.
    A 149/2 Correct Answer Incorrect Answer
    B 159/2 Correct Answer Incorrect Answer
    C 149/2 Correct Answer Incorrect Answer
    D 169/2 Correct Answer Incorrect Answer

    Solution

    4x + 1/3x = 12 Multiply by 3/4 3x + 1/4x = 9 Squaring on both sides (3x + 1/4x)2 = 81 9x2 + 1/16x2 +2(3x)(1/4x) = 81 9x2 + 1/16x2 = 81 – 3/2 9x2 + 1/16x2 = 159/2

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