$\lim_{x\to4}\left(\frac{4-x}{5-\sqrt{x^2+8}}\right)$

$\left(3a^2-2a+5\right)\left(m+n\right)+\left(3a^2-2a+5\right)\left(2m-3n\right)$

$\frac{dy}{dx}=\frac{1-y}{1+x}$

$5xb+5by-3ax-3ay$

$\cos\left(\frac{4\pi}{9}\right)cos\left(\frac{\pi}{9}\right)+\sin\left(\frac{4\pi}{9}\right)sin\left(\frac{\pi}{9}\right)$

$f\left(x\right)=\frac{6x-2}{6x^2-7x-3}$

$25y^2z^4-121$