$\frac{1}{csc\theta\:+1}-\frac{1}{csc\theta\:-1}=-2tan^2\theta\:$

$2\int\frac{x}{e^x}dx$

$\left(2-\frac{3}{2}y\right)^2$

$\left(-u+2\right)\left(u+2\right)$

$\lim_{x\to\frac{\pi}{2}}\left(\frac{x\left(1-sin\left(x\right)\right)}{\cos\left(x\right)}\right)$

$2a+2\sqrt{a}\sqrt{a+1}-1$

$4a+b-2a^2+b$