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    Question

    If p + q = 7 and p2 + q2 = 19,

    then find the value of  pq/2.
    A 7.5 Correct Answer Incorrect Answer
    B 3.6 Correct Answer Incorrect Answer
    C 10 Correct Answer Incorrect Answer
    D 12 Correct Answer Incorrect Answer

    Solution

    We have given, p + q = 7 and p2 + q2 = 19 So, (p + q) = 7 Or, p2 + q2 + 2pq = 72 [Since we know that, (a + b)2 = a2 + b2 + 2ab] Or, 19 + 2pq = 49 Or, 2pq = 49 - 19 Or, 2pq = 30 Or, pq = 15 Now, pq/2 = 15/2 = 7.5

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