📢 Too many exams? Don’t know which one suits you best? Book Your Free Expert 👉 call Now!

    ⚡ Rakhi Special - Flat 52% off on All Courses from 6 to 10 Aug! ⚡ Enroll Now

    Question

    If (x + y + z) = 10 and (x 2  + y 2

     + z 2 ) = 52, then find {z(x + y) + xy}.
    A 36 Correct Answer Incorrect Answer
    B 32 Correct Answer Incorrect Answer
    C 48 Correct Answer Incorrect Answer
    D 24 Correct Answer Incorrect Answer

    Solution

    Since, (x + y + z) 2  = x 2  + y 2  + z 2  + 2(xy +yz +zx)

    So, (10) 2   = 52 + 2(xy +yz +zx)

    Or, 100 - 52 = 2(xy +yz +zx)

    Or, 48 = 2(xy +yz +zx)

    Or, 24 = (xy +yz +zx)

    So, z(x + y) + xy = 24

    Practice Next
    More Algebra Questions
    ask-question