SSC CPO 2022 PYQ — Question 138

SSC CPO - 10 Nov 2022 - Shift 3 • Quantitative Aptitude • Q138

If x8+1x4x^8 + 1 \over x^4 = 14, then the value of x12+1x6x^12 + 1 \over x^6 is:

Show answer & explanation

Correct answer: C

Explanation

The correct answer is option 3 i.e. 52

If x8+1x4x^8 + 1 \over x^4 = 14

x4 + 1/x4 = 14

x2 + 1/x2 = √(14 + 2) = √16 = 4

The value of x12+1x6x^12 + 1 \over x^6

x6 + 1/x6 = (x2 + 1/x2)3 - 3  (x2 + 1/x2)

= 64 - 3 * 4 = 64 - 12 = 52