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SSC CGL 2019 PYQ — Question 52

SSC CGL - 13th June 2019 - Shift 1 • Quantitative Aptitude • Q52

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If (a – b) = 4 and ab = 2, then (a3– b3) is equal to:

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Correct answer: D

Explanation

The correct answer is option 4 i.e. 88.

⇒ (a – b)3 = a3 – b3 – 3ab(a – b)

Given,

⇒ (a – b) = 4 and

⇒ ab = 2

Applying the formula:

⇒ 43 = a3 – b3 – (3 × 2 × 4)

⇒ a3 – b3 = (64 + 24)

⇒ a3 – b3 = 88