$18a^2\:-\:12ab\:+\:8b^2$

$\tan\left(180\right)=\frac{\sin\left(180\right)}{\cos\left(180\right)}$

$\frac{d}{dx}21x^2=5y^2+3y$

$\lim_{x\to\infty}\left(\frac{2ln\left(x\right)}{x^2\cdot e^2}\right)$

$27a^3b^2-9a^2b$

$\left(\frac{\sec\left(x\right)}{\csc\left(x\right)}\right)^2\cdot\frac{\cos\left(x\right)}{\sin\left(x\right)}=\tan\left(x\right)$

$y=\frac{1}{2}\:\left(1+4e^{-2t}\right)$