$5+8.6$

$\cos\left(a\right)=\frac{\left(\cos\:\left(3a\right)+\cos\:\left(a\right)\right)}{2\cos\left(2a\right)}$

$\lim_{x\to\infty}\left(\frac{e^{3x^2}}{x^3+2}\right)$

$\lim_{z\to\infty}\left(ze^z\right)$

$-2\sqrt{x}+\frac{4-x}{\sqrt{x}}$

$2^3\cdot2^3.2^{-4}$

$.\:\left(n^3\:+\:5\right)^2$