$\frac{d^{21}}{dx^{21}}\left(2\cos\left(x\right)-3\sin\left(x\right)\right)$

$\lim_{x\to\infty}\:-2^{x-1}$

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

$3x^3-20x^2+37x-20$

$h-xy-\frac{3}{x};\:x=7;\:y-6;\:h=-5$

$\int\sqrt{4+25y^2}dy$

$-4u+4=4\left(u-3\right)$