Use the method discussed under "Homogeneous Equations" to solve Problems $9-16.$

$9.(xy+y^2)dx-x^{2}dy=0$

$10.(3x^2-y^2)dx+(xy-x^3{y}^{-1})dy=0$

$11.(y^2-xy)dx+x^{2}dy=0$

$12.(x^2+y^2)dx+2xydy=0$

$13.\frac{dx}{dt}=\frac{x^2+t\sqrt[\phantom{2}]{t^2+x^2}}{tx}$

$14.\frac{dy}{d}=\frac{sec(\frac{y}{})+y}{}$