$\left(x+3x^3\sin\left(y\right)\right)dx+\left(\frac{3}{4}x^4\cos\left(y\right)\right)dy=0$

$\frac{2}{3}x^2\left(3x-9\right)$

$\left(\frac{1}{3}x^2+\frac{2}{3}y^2\right).\left(ax+bx+ay\right)$

$-5y\:+\:4+t=\frac{dy}{dt}$

$\frac{1-cos^2x}{sen^2+cos^2x}+senx$

$if\:f\left(x\right)=\frac{1}{x}$

$ay\:dx+\:bx\:dy=0$