$-12-3-7+4-2+1+5$

$\left(\left(6x\left(2x+1\right)\right)-\left(5\left(2x+1\right)\right)\right)$

$27a^3b^2c+9ab^3c^2$

$\lim_{x\to0}\left(\frac{3sin\left(2x\right)+4tan\left(3x\right)}{\sqrt{x}}\right)$

$4b+6a-2b-3a+4a-5b$

$\left(5x\right)\left(-3x\right)$

$\cos\left(4\right)-\sin\left(4\right)=\cos2$