Question

    Find ‘x’ if (x³+3x)/(3x²+1) =

    189/61
    A 7 Correct Answer Incorrect Answer
    B 9 Correct Answer Incorrect Answer
    C 2 Correct Answer Incorrect Answer
    D 5 Correct Answer Incorrect Answer

    Solution

    Applying componendo and dividendo, (x³+3x+3x²+1)/(x³+3x-3x²-1) = (189+61)/(189-61)=250/128 ⇒ ((x+1)³)/((x-1)³) = 125/64 ⇒ (x+1)/(x-1) = 5/4 ⇒ x/1 = (5+4)/(5-4) ⇒ x = 9

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