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SSC CHSL 2023 PYQ — Question 70

SSC CHSL - 10 March 2023 - Shift 2 • Quantitative Aptitude • Q70

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If (a - b) = 5 and ab = 150, then what is the value of (a3 - b3)?

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Correct answer: C

Explanation

The correct answer is option 3 i.e. 2375.

(a - b) = 5

⇒ (a - b)2 = 52

⇒ a2 - 2ab + b2 = 25

⇒ a2 - 2(150) + b2 = 25

⇒ a2 - 300 + b2 = 25

⇒ a2 + b2 = 325

Now, a3 - b3 = (a - b)(a2 + ab + b2) = 5(325 + 150) = 5 × 475 = 2375