$21ab+10ab^2-101a^2$

$\lim_{x\to\frac{\pi}{2}}\left(\sec\left(x\right)\right)^{\cot\left(x\right)}$

$\int x^2\sin\left(-6x\right)dx$

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

$\left(4c^2\cdot c^3\cdot3c\right)^2$

$\lim_{x\to0}\left(\frac{\left(\left(-19\right)^x\cdot x^2\right)}{x+21}\right)$

$-\frac{4-x}{2}\le\frac{3}{4}x+\frac{1}{2}$