Questions asked
\( \begin{array}{l}\frac{y d y}{x d x}=\sqrt{1+x^{2}+y^{2}+x^{2} y^{2}} \\ x(1-y) d x+\left(1+y^{2}\right)(x-1) d y=0 \\ \frac{d y}{d x}=e^{x+y}+x^{2} e^{y}\end{array} \)
