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    Question

    What will come in the place of question mark (?) in the given expression?

    [1.45 X 1.45 X 1.45 + 0.55 X 0.55 X 0.55 + 4.785] =

    ?
    A 6 Correct Answer Incorrect Answer
    B 8 Correct Answer Incorrect Answer
    C 12 Correct Answer Incorrect Answer
    D 10 Correct Answer Incorrect Answer
    E None of these Correct Answer Incorrect Answer

    Solution

    ATQ, [1.45 X 1.45 X 1.45 + 0.55 X 0.55 X 0.55 + 4.785] = [(1.45)3 + (0.55)3 + 3 X 1.45 X 0.55 X 2] = [(1.45)3 + (0.55)3 + 3 X 1.45 X 0.55(1.45 + 0.55)] This of the form (a3 + b3 ) + 3ab(a + b), where 'a' = 1.45 and 'b' = 0.55 And, hence, required value = (a + b)3 = (1.45 + 0.55)3 = (2)3 = 8

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