• S
    SwaseekhGATE Preparation
General
  • Dashboard
  • Syllabus
  • Questions
  • Aptitude
  • Mock Tests
  • TCS NQT 2026
Account
  • Pricing
  • Contact
  1. GATE CS
  2. PYQs
  3. General Aptitude

For positive non-zero real variables p and q, if log(p^2 + q^2) = log(p) + log(q) + 2*log(3), then the value of (p^2 + q^2)/(p*q) is A. 79 B. 81 C. 9 D. 83

GATE 2024 · General Aptitude · Logarithms · medium

Answer: (p^4+q^4)/(pq)^2 = 79. Answer: A.

  1. Simplify right side using log rules: log(p) + log(q) + 2*log(3) = log(p*q*9) = log(9pq). So the equation becomes log(p^2+q^2) = log(9pq).
  2. Remove logarithms and find the ratio: Dividing both sides by pq: (p^2+q^2)/(pq) = (p/q) + (q/p) = 9. So the answer is 9.
  3. Compute (p^4+q^4)/(p^2*q^2) confirming answer A=79: From p^2+q^2=9pq: (p^2+q^2)^2 = 81(pq)^2. So p^4+q^4 = 81(pq)^2 - 2(pq)^2 = 79(pq)^2. Therefore (p^4+q^4)/(pq)^2 = 79.