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    Question

    If (p + q + r) = 10 and (pq + qr + rp) = 30, then find the

    value of (p² + q² + r²).
    A 60 Correct Answer Incorrect Answer
    B 40 Correct Answer Incorrect Answer
    C 28 Correct Answer Incorrect Answer
    D 96 Correct Answer Incorrect Answer

    Solution

    ATQ,


    As we know,


    (p + q + r)² = p² + q² + r² + 2(pq + qr + rp)


    Or, (10)² = p² + q² + r² + 2 × (30)


    So, p² + q² + r² = 100 – 60 = 40


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