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

$\lim_{x\to0}\left(\frac{sen\left(4x\right)}{x}\right)$

$10+\left(6\cdot5\right)$

$\frac{6\left(x-1\right)+x\left(-1+x\right)}{x\left(x+6\right)+2\left(6+x\right)}$

$5\:-\:2\:+\:r$

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

$-\frac{4}{7}+\frac{2}{7}x\:-14x\:+\frac{4}{7}$