$6a^3+3a^3+2a^3$

$\lim_{x\to5}\left(3x\:-7\right)$

$\frac{\sin\:\left(\theta\:\right)}{1-\cos\:\left(\theta\:\right)}=\frac{1+\cos\:\left(\theta\:\right)}{\sin\:\left(\theta\:\right)}$

$\int_0^{\infty}\left(\frac{x^{-1}+x^{-2}}{1+x^2}\right)dx$

$x^2-4-117$

$\int_{-6}^0\left(14x+13\right)dx$

$x^2+xy^2\cdot x-y$