$15a^2\left(a+1\right)^3-5a^3\left(a+1\right)^2$

$2x\:+\:2<10$

$\frac{1-3\cos\:\:x-4\cos\:^2x}{\sin\:^2x}=\frac{1-4\cos\:\:x}{1-\cos\:\:x}$

$100a^2+80a+16-49n^2+210n-225$

$\left(4+x\right)\frac{dy}{dx}=2y$

$\frac{d}{dx}\sqrt{4-x^2}$

$\sin\left(\pi-x\right)=\sin\left(x\right)$