$x^2+0x-4$

$x-\frac{x^2}{2}+\frac{x^3}{3}-\ln\left(x+1\right)$

$\frac{x^2}{x^2+6}$

$3x-2x=13$

$\frac{1}{\left(n^2+n-20\right)}$

$\frac{d}{dt}\left(\frac{cos\left(t\right)}{t}\right)$

$-\:\left[-8\:-\:\left(+3\right)\:\left(-8\right)\:-\:\left(-\:4\right)\:\right]\:-\left[\:\left(-\:5\right)\:\left(-\:4\right)\:-\:\left(+12\right)\:\right]$