$\frac{20a^2b^2}{-10a^5b}$

$2x^2+2y^2-2z^2-5xy-5xz+3yz+0$

$\frac{\left(sin^2x-3cos^2x+1\right)}{sin^2x-cos^2x}=2$

$\left(7x+2y+4\right)^2$

$\cos x\left(1-\cos2x\right)$

$\lim_{x\to2}\left(\frac{x^2-1}{\sqrt{x}-1}\right)$

$\sin\left(120\right)\cdot\cos\left(225\right)$