SarkariPYQ

SSC CHSL 2021 PYQ — Question 66

SSC CHSL - 19 April 2021 - Shift 3 • Quantitative Aptitude • Q66

Back to paper

If x8−2599x4+1=0,{{x^8-2599x^4+1=0,}} then the positive value of x−1xx - {{1} \over x}will be:

Show answer & explanation

Correct answer: C

Explanation

The correct answer is Option 3 i.e. 7.

Given that 

If x8−2599x4+1=0{{x^8-2599x^4+1=0}}

x8+1=2599x4{{x^8+1=2599x^4}}

x4+1x4=2599{{x^4+\frac{1}{x^4}=2599}}

 x2+1x2=51{{x^2+\frac{1}{x^2}=51}}

x−1x=7{{x-\frac{1}{x}= 7}}