$\cosh\left(x+y\right)=\cosh\left(x\right)\cosh\left(y\right)+\sinh\left(x\right)\sinh\left(y\right)$

$\lim_{x\to\infty}\frac{x^2+3x-18}{x^2-9}$

$\int_{-\infty}^0\left(\frac{-36x}{\left(3x^2+1\right)^4}\right)dx$

$\lim_{x\to-\frac{2}{3}}\left(\frac{6x^2-13x-6}{9x^2-4}\right)$

$a^2-a+30$

$-15-60$

$\int\left(9x^2+6x+3\right)dx$