$log\left(2x+5\right)+log\left(x-3\right)=1$

$2x+1\:para\:x=0$

$\frac{d}{dx}\left(cos\left(xy\right)=y^2+2x\right)$

$f\left(x\right)=6x-2$

$\frac{d}{dx}\left(\frac{cos^2x-sen^2\left(2x\right)}{4cos^2x}\right)$

$\left(3a+b+2c\right)^2$