SarkariPYQ

SSC CPO 2023 PYQ — Question 128

SSC CPO - 05 Oct 2023 - Shift 2 • Quantitative Aptitude • Q128

Back to paper

If a - 1a\frac{1}{a} = 4, then the value of a + 1a\frac{1}{a} is:

Show answer & explanation

Correct answer: C

Explanation

The correct answer is option 3 i.e.  25\sqrt{5} .

Given that

If a - 1a\frac{1}{a} = 4

Square both sides

⇒ a2 + 1a2\frac{1}{a^2} -  2 = 16

⇒  a2 + 1a2\frac{1}{a^2} = 16 + 2 = 18

⇒  (a + 1a\frac{1}{a} )2 - 2 = 18

⇒  (a + 1a\frac{1}{a} )2 = 18 + 2 = 20

⇒  a + 1a\frac{1}{a} = √20 =  25\sqrt{5}