Exams › SSC CGL (Prelims) › General

If a + b = 25 and ab = 20, find the value of a^3 + b^3.

1. 13152
2. 13125
3. 14125
4. 14152

Correct answer: 14125

Solution

Using the algebraic identity a^3 + b^3 = (a+b)^3 - 3ab(a+b): substitute a+b = 25 and ab = 20 to get 25^3 - 3(20)(25) = 15625 - 1500 = 14125.

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