$\left(3zy^3-4x^2\right)\:^3$

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

$-3x^2ym+7x-ymx^2+16x$

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

$r^2+r+5=0$

$15x^2-55x-20$

$\frac{dy}{dx}+\frac{2xy}{1+x^2}=\frac{1}{\left(1+x^2\right)^2}$