$\lim_{x\to-1}\left(\arctan\left(\frac{x-1}{x+1}\right)\right)$

$\lim_{x\to25}\left(\frac{\sqrt{x+5}}{x+25}\right)$

$8x-7=33$

$8x^2+12xy+2zy$

$\frac{-36x^4y}{6x^3y^2}$

$\left(-3\right)^4-\left(-2\right)^3$

$\lim\:_{x\to\:2}\left(\frac{ln\left(cos\left(2x-4\right)\right)}{ln\left(cos\left(x-2\right)\right)}\right)$