$3a^4+a^3+15a+5$

$\lim_{x\to-1.5}\left(\frac{9-4x^2}{3+2x}\right)$

$\frac{dy}{dx}=-\frac{y+2xy^3}{1+x+3x^2y^2}$

$\left(x-18\right)\left(x+13\right)$

$\left(-2\right)\left(8\right)\left(-5\right)\left(-5\right)$

$\cot\left(x\right)\tan\left(x\right)cot\left(x\right)tan\left(x\right)$

$\frac{dy}{dx}=\frac{1}{2}x^3$