$\frac{\left(cos\left(x+h\right)-cos\left(x\right)\right)}{h}$

$400a^4-\frac{16}{16}$

$\lim_{x\to6}\left(\frac{x^3-6t+180}{x^2-t-42}\right)$

$3x^2=4yx$

$\left(\frac{d^3}{dx^3}\left(\frac{1}{3}x^3+\frac{3}{20}x^6+\frac{1}{24}x^{-4}\right)\right)$

$\frac{\sqrt{\left(x-2\right)+\left(x+3\right)}}{2}$

$\left(-9x+9\right)$