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    • Question

      If p = 30 - q - r and pq + r(q + p) = 296 then find the

      value of (p 2  + q 2  + r 2 ) .
      A 298 Correct Answer Incorrect Answer
      B 316 Correct Answer Incorrect Answer
      C 308 Correct Answer Incorrect Answer
      D 288 Correct Answer Incorrect Answer

      Solution

      We have, p = 30 - q - r
      So, p + q + r = 30
      And, pq + r(q + p) = 296
      Or, pq + qr + pr = 296
      Using, (p + q + r)  2  = p 2  + q 2  + r 2  + 2(pq + qr + pr)
      So, 30 2  = (p 2  + q 2  + r 2 ) + 2 X 296
      Or, p 2  + q 2  + r = 900 - 592
      Or, p 2  + q 2  + r 2  = 308

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