SSC CHSL 2021 PYQ — Question 71

The correct answer is option 4 i.e. 142

Given:

x⁴ - 12x² + 1 = 0

Explanation:

Dividing the given x⁴ - 12x² + 1 = 0 by x², we get

$x^2 + { 1\over x^2} = 12$

Squarying both sides we get

$x^4 + {1\over x^4} + 2 = 144$

⇒  x⁴ $+\frac{1}{x^4}$ = 144 - 2

⇒ x⁴ $+\frac{1}{x^4}$ = 142

Hence the required answer is 142.