$e^{-ax}e^x$

$\lim_{x\to3}\left(\frac{3-x}{1-\sqrt{4-x}}\right)$

$\frac{d^2}{dx^2}\left(e^a\cdot\cos\left(g\right)\right)$

$\left(3x-2\right)\left(3x-1\right)+2$

$\frac{1-\cos\left(y\right)}{1+\sec\left(y\right)}$

$\left(x+10x+18\right)+\left(x+5\right)$

$\left(2a^2+3a-15\right)-\left(13a-9\right)$