SSC CGL 2023 PYQ — Question 73

SSC CGL - 20 July 2023 - Shift 4 • Quantitative Aptitude • Q73

If (x − 1x\frac{1}{x} ) = 6, and x > 0, find the value of (x² - 1x2\frac{1}{x^2}).

Show answer & explanation

Correct answer: A

Explanation

The correct answer is option 1 i.e. 1210\sqrt{10}.

Given that

If (x − 1x\frac{1}{x} ) = 6, and x > 0,

Squaring both sides

⇒ x2 + 1/x2 - 2 = 36

Adding 4 on both sides

⇒ x2 + 1/x2 - 2 + 4 = 36 + 4 = 40

⇒ (x + 1/x)2 = 40

⇒ x + 1/x = 210\sqrt{10}

Hence, the value of   (x² - 1x2\frac{1}{x^2}) = (x + 1/x) (x - 1/x) =  210\sqrt{10} × 6 = 1210\sqrt{10}