Exams › SSC CGL (Prelims) › General

If \(a^3 + b^3 = 91\) and \(ab = 12\), find the value of \(a+b\).

1. 6
2. 7
3. 8
4. 9

Correct answer: 7

Solution

Using \(a^3+b^3=(a+b)^3-3ab(a+b)\), let \(a+b=s\). Then \(91=s^3-36s\). Testing the options, \(s=7\) gives \(343-252=91\), so \(a+b=7\).

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