$x^2+1+81$

$81a^6+36-108$

$\lim_{x\to0}\left(\frac{ln\left(cos\left(x-2\right)\right)}{1-sen\left(\frac{\pi}{4\:}x\right)}\right)$

$-\:\left(1\:\:-\:2\:-\:3\right)\:-\:\left(5\:-\:5\:+\:4\:+\:6\:+\:8\right)$

$\int\frac{1}{\left(x-1\right)\left(x+1\right)\left(x^2+1\right)^2}dx$

$24-\left(+8+3-6\right)$

$\frac{1x^3}{x^{-2}}$