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SSC CGL 2019 PYQ — Question 71

SSC CGL - 11th June 2019 - Shift 2 • Quantitative Aptitude • Q71

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If a + b + c = 6 and ab + bc + ca = 4, then a3 + b3 + c3 - 3abc is equal to:

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Correct answer: A

Explanation

The correct answer is Option 1 i.e. 144

Concept

Understanding

Application

a3 + b3 + c3 - 3abc = (a + b +c) [(a + b + c)2 - 3(ab + bc + ca)]

Given, a + b + c = 6 and ab + bc + ca = 4

a3 + b3 + c3 - 3abc = 6 [62 - 3 × 4]

⇒ 6 (36 - 12)

⇒ 6 × 24

⇒ 144