SSC CGL 2021 PYQ — Question 62

The correct answer is option 3 i.e. 184

Given :

 (2x- $\frac{3}{x}$ ) = 2

Formula used :

(a + b)² = a² + b² + 2ab      ---- (1)

Calculations :

Using equation (1)

⇒  (2x- $\frac{3}{x}$)² = 4x² + (9/x²) - 2(2x)(3/x)

⇒ 4 = 4x² + 9/x² - 12

⇒ 16 =  4x² + 9/x²        ----- (2)

Using equation (1) in equation (2)

⇒ (4x² + 9/x²)² = 16x² + 81/x⁴ + 2(4x²)(9/x²)

⇒ 256 = 16x² + 81/x⁴ + 72

⇒ 16x² + 81/x⁴ = 256 - 72

⇒ 184