$\sin\left(\frac{\pi}{6}+x\right)+\sin\left(\frac{\pi}{6}-x\right)=\cos\left(x\right)$

$\left(-2z-9\right)\left(7z+9\right)$

$36\left(m+n\right)^2-12\left(m-n\right)^2$

$-10\:-\:\left(5\:-\:\left(-8\right)\right)$

$\lim_{x\to0}\left(\frac{x}{\left(lnx\right)^3}\right)$

$9x^2-2x+16x-72x^2$

$-x^2+6=x^2+4x$