But denominator is :mrgreen:Loren said:Typo someplace?
Your original expression comes out as...
\(\displaystyle \frac{(1-xy)+(x+y)\cdot y}{(1-xy)^2+(x+y)^2}=\frac{1-xy+xy+y^2}{1-2xy+x^2y^2+x^2+2xy+y^2}=\frac{1+y^2}{1+x^2y^2+x^2+y^2}\)
Numerator is not factorable.
mathematica says:
1/(1+x^2)