$\lim_{x\to0}\left(\frac{2t^2+3t}{t^2-5}\right)$

$\left(3x^3\right)^3-\left(y^3\right)^3$

$-\csc\left(x\right)\cdot\cot\left(x\right)$

$16-8c^4+c^8$

$\frac{90r^3+145r^2+77r+29}{9r+10}$

$\sin\left(x-\frac{\pi}{4}\right)=\frac{\sqrt{2}}{2}\left(\sin\left(x\right)-\cos\left(x\right)\right)$

$\lim_{x\to\frac{\pi}{2}}\left(\cos\left(2x\right)^{\frac{x-\pi}{2}}\right)$