$sin\left(\frac{2}{5}\right)cos\left(-\frac{1}{8}\right)+cos\left(\frac{2}{5}\right)sin\left(-\frac{1}{8}\right)$

$5x\cdot\left(x^2-3\right)-2\cdot\left(-x^2-6x-5\right)$

$\frac{-2x^3+16x}{2\sqrt{4-x^2}}$

$7.4 z - 5 ( - 1.6 z + 2.4 )$

$\lim_{x\to\infty}\left(\frac{e^{5x}-1-5x}{x^2}\right)$

$\lim_{x\to\infty}\:\frac{3x^2+5}{x^2-2}$

$\cos^2\left(\frac{\pi}{2}\right)$