$x\frac{dy}{dx}+y=x^2y^3$

$\left(-x^4+8x^2+9\right)^2$

$a^8+a^8a^4+81$

$\lim_{x\to\pi}\left(\frac{1+\cos\left(2x\right)}{1-sen\left(\frac{\pi\:}{2}\right)}\right)$

$0=\frac{1-\ln\left(\ln\left(x\right)\right)}{x^2}$

$\frac{d}{dx}\left(cosh\left(x+y\right)=y\:senhx\right)$

$\lim_{x\to\frac{\pi}{2}}\left(\frac{\cos\left(x\right)-\frac{1}{2}}{x-\frac{\pi}{3}}\right)$