Exercises$1$ "Integrating Factor by Inspection"

In problems $(1-13),$ solve the equation

$y(2xy1)dx-xdy=0$

$y(y^3-x)dxx(y^{3}x)dy=0$

$2tdss(2s^{2}t)dt=0$

$y(x^4-y^2)dxx(x^4{y}^2)dy=0$

$y(y^{2}1)dxx(y^2-1)dy=0$

$xydx2(x^{2}2y^2)dy=0$

$ydx2(y^4-x)dy=0$

$[1ytan(xy)]dxxtan(xy)dy=0$

$y(x^3{e}^{xy}-y)dxx(y{x}^3{e}^{xy})dy=0$

$y^{\text{'}}=ytanxcosx$

$(x^3{y}^3)dx{y}^2(3xky)dy=0$

$(xsi{n}^{2}y)dxxsin2ydy=0$

$(siny-ysinx)dx(cosxxcosy)dy=0$