SSC CGL 2025 PYQ — Question 70

SSC CGL - 19 Sep 2025 - Shift 3 • Quantitative Aptitude • Q70

Given: x+​​1x=−2x+​​\frac{1}{x}=-2, then determine the value of x6+1x6−3(x4+1x4)+4(x2+1x2)x^6+\frac{1}{x^6}-3\left(x^4+\frac{1}{x^4} \right)+4\left(x^2+\frac{1}{x^2} \right)

Show answer & explanation

Correct answer: D

Explanation

The correct answer is option 4 i.e. 4.

x+​​1x=−2x+​​\frac{1}{x}=-2

⇒ (x+1x)2=(−2)2=4\left(x+\frac{1}{x} \right)^2=(-2)^2=4

⇒ x2+1x2=4−2=2x^2+\frac{1}{x^2}=4-2=2

(x4+1x4)=(x2+1x2)2−2=22−2=2\left(x^4+\frac{1}{x^4} \right)=\left(x^2+\frac{1}{x^2} \right)^2-2=2^2-2=2

(x6+1x6)=(x2+1x2)3−3(x2+1x2)=23−3(2)=8−6=2\left(x^6+\frac{1}{x^6} \right)=\left(x^2+\frac{1}{x^2} \right)^3-3\left(x^2+\frac{1}{x^2} \right)=2^3-3(2)=8-6=2

x6+1x6−3(x4+1x4)+4(x2+1x2)x^6+\frac{1}{x^6}-3\left(x^4+\frac{1}{x^4} \right)+4\left(x^2+\frac{1}{x^2} \right)

= 2 - 3(2) + 4(2)

= 2 - 6 + 8

= 4