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SSC CGL 2019 PYQ — Question 55

SSC CGL - 11th June 2019 - Shift 2 • Quantitative Aptitude • Q55

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If (a + b) = 6 and ab = 16/3, then (a3 + b3) is equal to:

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Correct answer: C

Explanation

The correct answer is option 3 i.e. 120.

⇒ (a + b)3 = a + b + 3ab(a + b)

Given, (a + b) = 6 and 

⇒ ab = 16/3

⇒ (a + b) = 6,  Taking cube on both sides:

⇒ (a3 + b3) + 3 × 16/3 × 6 = 63

⇒ (a3 + b3) = (216 - 96) = 120