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    • Question

      If p = 40 - q - r and pq + r(q + p) = 432, then find

      the value of (p² + q² + r²).
      A 704 Correct Answer Incorrect Answer
      B 716 Correct Answer Incorrect Answer
      C 728 Correct Answer Incorrect Answer
      D 736 Correct Answer Incorrect Answer

      Solution

      We have, p = 40 - q - r So, p + q + r = 40 And, pq + r(q + p) = 432 Or, pq + qr + pr = 432 Using, (p + q + r)² = p² + q² + r² + 2(pq + qr + pr) So, 40² = (p² + q² + r²) + 2 × 432 Or, 1600 = (p² + q² + r²) + 864 Or, p² + q² + r² = 1600 - 864 Or, p² + q² + r² = 736

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