SarkariPYQ

SSC CGL 2019 PYQ — Question 62

SSC CGL - 6th June 2019 - Shift 1 • Quantitative Aptitude • Q62

Back to paper

If x = a + 1/a and y = a – 1/a then √(x4 + y4 - 2x2y2) is equal to:

Show answer & explanation

Correct answer: D

Explanation

Correct Answer is option 4 i.e. 4

Concept

Understanding

Application

x2 + y2 – 2xy = (x – y)2

Given

x = a + 1/a and y = a – 1/a

⇒ √(x4 + y4 – 2x2y2)

⇒ √(x2 – y2)2 

⇒ x2 – y2 

⇒ (x – y)(x + y)

⇒ (a + 1/a – a + 1/a) (a + 1/a + a – 1/a)

⇒ 2/a × 2a 

⇒ 4