Exams › SSC CGL (Prelims) › General

If a + b = 6 and ab = 4, find the value of 3(a^3 + b^3).

1. 512
2. 144
3. 288
4. 432

Correct answer: 432

Solution

Using the identity a^3 + b^3 = (a+b)[(a+b)^2 - 3ab]: a^3+b^3 = 6[36-12] = 6 x 24 = 144. Multiplying by 3 gives 3 x 144 = 432.

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