$\frac{2x^3\left(x-3\right)}{5\left(x+3\right)}$

$7x^2-70xy+175y^2$

$\lim_{x\to-\infty}\left(\left(1-\frac{2x}{x^{2}-1}\right)^{-4x}\right)$

$\int\frac{1}{2\sqrt{1+x}}dx$

$\frac{d}{dr}\sqrt{b^2-r^2}+b$

$\lim_{x\to0}\left(\frac{4xcosx-4sinx}{xsinx}\right)$

$\int\frac{5z}{3z^3+6z^2+z+2}dz$