If x/y = 6/5 then the value of $$\frac{x^2 + y^2}{x^2 -y^2}$$ is:

Given: 

​$$\frac{x}{y} =\frac{6}{5}$$ 

To find: $$\frac{x^2+y^2}{x^2-y^2}$$ 

Solution: 

Let the value of x = 6k, y = 5k 

Putting this in expression;

​$$=\frac{(6k)^2+(5k)^2}{(6k)^2 -(5k)^2} \\ \ \\= \frac{36k^2 + 25k^2}{36k^2 - 25k^2}\\ \ \\ = \frac{61 \cancel {k^2}}{11\cancel {k^2}} \\ \ \\ = \frac{61}{11}$$​​​​