$$9n^2-12n+4$$

$$cos\left(\frac{\pi\:}{3}+x\right)+cos\left(\frac{\pi\:}{3}-x\right)=cos\left(x\right)$$

$$\cos^2x-0.5$$

$$4x+x^2=2z^3-4z$$

$$m^2+6mn+9n^2$$

$$\frac{dy}{dx}+64=e^{-4x}$$