SSC CGL 5th March 2020 Shift-3

Question 64

If $$x - \frac{1}{x} = 11$$, then $$x^3 - \frac{1}{x^3}$$ is:

Solution

$$x - \frac{1}{x} = 11$$

$$x^3 - \frac{1}{x^3}$$ = $$(x - \frac{1}{x})^3 - 3(x - \frac{1}{x})$$

($$\because (a - b)^3 = a^3 - b^3 -3ab(a - b)$$)

= $$(11)^3 - 3(11)$$

= 1331 - 33 = 1298

Share on Whatsapp Share on Whatsapp

Create a FREE account and get:

  • Free SSC Study Material - 18000 Questions
  • 230+ SSC previous papers with solutions PDF
  • 100+ SSC Online Tests for Free

cracku

Boost your Prep!

Download App