$5x\:-2\:por\:x=1$

$\lim_{x\to0}\left(\frac{e^x\sin\left(x\right)-1}{\ln\left(x+1\right)}\right)$

$\frac{9}{1+\cos^2\left(x\right)}=\frac{9\sin^2\left(x\right)}{\left(1+\cos\:^2\left(x\right)\right)^2}$

$5xy\frac{dy}{dx}+y=0$

$x^2+13x+42=0$

$x^2-4x\ge12$

$y'=\frac{xy-3y+x-3}{xy+2y-x-2}$