$12x^3-16x^6$

$\cos x-\left(\cos x\cdot\sin^2x\right)$

$29\left(74-76\right)$

$\frac{d^2}{dy^2}\left(x^2\cdot e^{3xy}+4xz^3\right)$

$\frac{x^4-x^3-2x}{x+3}$

$\frac{24}{3}-\frac{9}{3}\left(\frac{24}{4}+\left(\frac{125}{5}-\left(\frac{7}{1}+\frac{30}{15}\right)\:\frac{2}{2}\right)\right)$

$\left(3u^4-18u^3\right)\left(u-2\right)$