$\lim_{x\to\infty}\left(x^3+6x-\left(x^2+4\right)^{\frac{3}{2}}\right)$

$10x^3\cdot x$

$f\left(x\right)=\frac{x^2+x+1}{\left(x+1\right)\left(x+2\right)\left(x-3\right)}$

$\left(3x^2-5x+14\right)\left(2x-17\right)$

$\frac{d}{dx}600-\sqrt{x^2+80}$

$\frac{5x^2-36+48}{x\left(x-4\right)^2}$

$\frac{x^2-2x-3}{x-1}$