$cos\left(\frac{13\pi}{15}\right)cos\left(-\frac{\pi}{5}\right)$

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

$\frac{d}{dx}e^{x-y}=x\cdot y-100$

$\frac{2x^2+9x+7}{x+2}$

$\frac{y^2+3y}{x^2+1}$

$\cos\left(x\right)\cdot\tan\left(x\right)+1=\sin\left(x\right)+\cos\left(x\right)$

$\frac{x^{10}-1}{x-1}$