Find $\frac{x^2}{y^2}$ + $\frac{y^2}{x^2}$ If $\frac{x}{y}$ + $\frac{y}{x}$ = 3 Find $\frac{x^2}{y^2}$ + $\frac{y^2}{x^2}$ 
Any Ideas on how to begin ?

Start by squaring both sides of $\frac{x}{y}+\frac{y}{x}=3$. What happens to the cross terms?
