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.
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).
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.