$\lim_{x\to\infty}\:ln\left(2e^x+e^{-x}\right)-ln\left(e^x-e^{-x}\right)$

$\lim_{x\to\frac{1}{2}}\left|\frac{6\sin\left(2x-1\right)}{6x-3}\right|$

$\tan\left(60\right)=\frac{80}{x}$

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

$ex x^{-x^2}$

$\frac{2}{x+2}\:-2,2$

$7y^3+8y^2-2-6y^3+2y^2+5$