<s>[INST] What should be the method for solving and solution of $\frac{x^2+y^2}{x^2-y^2}$? If $\frac{x+y}{x-y}=3$
then $\frac{x^2+y^2}{x^2-y^2} = ?$
 [/INST] $\frac{x+y}{x-y}=3 \implies x=2y$
$\frac{x^2+y^2}{x^2-y^2} = \frac{5y^2}{3y^2}=\frac{5}{3}$
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