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    Question

    If a3 + b3 = 6240 and a + b = 30,

    then find the value of {(a + b)2 – 3ab}
    A 324 Correct Answer Incorrect Answer
    B 416 Correct Answer Incorrect Answer
    C 104 Correct Answer Incorrect Answer
    D 208 Correct Answer Incorrect Answer

    Solution

    Since, {(a + b)2 – 3ab} = a2 + b2 + 2ab – 3ab = a2 + b2 – ab And, (a3 + b3) = (a + b)( a2 + b2 – ab) So, (a2 + b2 – ab) = 6240/30 = 208

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