SSC CGL 2020 PYQ — Question 78

SSC CGL Tier II - Quant - 18 Nov 2020 • Quantitative Aptitude • Q78

If x - 3/x = 6, x ≠ 0, then the value ofx4−27x2x2−3x−3\frac{x^4 - \frac{27}{x^2}}{x^2-3x-3}  is:

Show answer & explanation

Correct answer: D

Explanation

The correct answer is option 4 i.e. 90

x - 3/x = 6..........(1)

On cubing both sides we get,

x3 - 27/x3 - 3 × x × 3/x(x - 3/x) = 216

x3 - 27/x3 - 54 = 216

x3 - 27/x3 = 270..............(2)

x4−27x2x2−3x−3\frac{x^4 - \frac{27}{x^2}}{x^2-3x-3},

On dividing the numerator and denominator by x we get,

= (x3 - 27/x3)/(x - 3/x - 3)

= 270/(6 - 3)

= 270/3 = 90.