$\lim_{x\to0}\left(\frac{\cos\left(x\right)}{\sin\left(x\right)}\right)$

$\lim_{x\to\infty}\left(\frac{1}{x^2}-2\arctan\left(\frac{1}{x}\right)\right)$

$\frac{-15t^4r^5}{5t^3r^4}$

$3a^2+a-4$

$\left(1+\tan\left(x\right)\right)\cos\left(x\right)+\left(1-\cot\left(x\right)\right)\sin\left(x\right)$

$\frac{d}{dx}x^2+6xy-2y^2=3$

$\lim\:_{x\to\:0}\left(\frac{m\sin\:\left(x\right)-\sin\:\left(mx\right)}{x\left(\cos\:\left(x\right)-\cos\:\left(mx\right)\right)}\right)$