$\left(9x^3+y^2z\right)\left(x^3y^4z\right)$

$x^4+6x^3+9x^2-4x-12$

$9x^2-30x+9$

$\frac{cosx}{1+\frac{sinx}{cosx}}$

$\int_0^{\frac{\sqrt{2}}{2}}\left(\frac{t^2}{\left(1-t^2\right)^{\frac{3}{2}}}\right)dx$

$\lim_{x\to0}\:x\:\left(arctg\left(e^x\right)-\frac{\pi}{2}\right)$

$\frac{\frac{x}{4}}{\frac{6}{x}}$