$\cos\left(x\right)=\frac{9}{5}$

$12m^4n^2-6m^3n^2+18m^2n^2$

$\left(xy-x\right)dx+dy=0$

$\lim_{x\to0}\left(\sin\left(x\right)\right)^{x^2}$

$2^3+2^0-2^2$

$2\sin\left(2x\right)\sin\left(x\right)-2\sin^2\left(x\right)-2\cos\left(x\right)=-1$

$\frac{dy}{dx}=\frac{\cos\left(x\right)}{y^2-1}$