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    Question

    If a, b, c are in geometric progression and a + b + c =

    14, a² + b² + c² = 84, find a, b, c.
    A 3,4,8 Correct Answer Incorrect Answer
    B 1,2,5 Correct Answer Incorrect Answer
    C 2,4,8 Correct Answer Incorrect Answer
    D 3,3,5 Correct Answer Incorrect Answer

    Solution

    ATQ,

    Let a = x, b = xr, c = xr² Sum: x(1 + r + r²) = 14 Squares: x²(1 + r² + r⁓) = 84 Divide 2nd by (1st)²: (1 + r² + r⁓)/(1 + r + r²)² = 84/14² = 84/196 = 3/7 Try r = 2 → (1+4+16)/(1+2+4)² = 21/49 = 3/7 āœ… Then x(7) =14 ⇒ x = 2 → (a,b,c) = (2,4,8)

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