$\lim_{x\to\infty}\left(\frac{3e^x-\sin\left(x\right)}{e^x+1}\right)$

$\left(\cos\left(x\right)+\sin\left(x\right)\right)^2-\left(2\left(\cos\left(x\right)\sin\left(x\right)-\left(\sin^2\left(x\right)+\cos^2\left(x\right)\right)\right)\right)$

$\int\left(\frac{a}{a-x}\right)dx$

$3\left(x-2\right)+5=4\left(x-1\right)$

$81-n^{10}$

$\int\frac{2}{\left(x+4\right)+\left(x+1\right)^2}dx$

$x^2+5x+19;\:x=3$