Exams › SSC CGL (Prelims) › General

If 2p + q = 19 and 8p^3 + q^3 = 361, find the value of pq.

1. 56
2. 59
3. 58
4. 57

Correct answer: 57

Solution

Let a=2p, b=q. a+b=19, a^3+b^3=361. Using a^3+b^3=(a+b)^3-3ab(a+b): 361=6859-3x19xab => 3x19xab=6498 => ab=114. So 2p*q=114 => pq=57.

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