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SSC CGL 2022 PYQ — Question 66

SSC CGL - 02 Dec 2022 - Shift 4 • Quantitative Aptitude • Q66

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If K + 1/K = 3, then what is the value of K3 + 1/K3?

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Correct answer: C

Explanation

The correct answer is option 3 i.e. 18

Given:

K + 1/K=3

Concept Used:

(a + b)3 = a3 + b3 + 3ab(a + b)   ....(i)

Explanation:

Using equation (i), we get

(K + 1/K)3 = (3)3

⇒ K3 + (1/K)3 + 3(K + 1/K) = 27

⇒ K3 + (1/K)3 + 3(3) = 27

⇒ K3 + (1/K)3 = 18

Hence the required value is 18.