Question 29

If xy(x+y)=1 then, the value of $$\frac{1}{x^{3}y^{3}}-x^{3}-y^{3}$$ is

Solution

xy(x+y)=1

x+y = 1/xy

apply cube on both sides,

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

$$x^{3}+y^{3}+3xy(x+y)$$ =  $$\frac{1}{x^{3}y^{3}}$$

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

                    3   =  $$\frac{1}{x^{3}y^{3}}$$ - $$x^{3}-y^{3}$$

so the answer is option A.


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