$3\sqrt{6}-15\sqrt{6}+8\sqrt{6}$

$\frac{1a}{-1}$

$\left(5x+4\right)\left(5x-8\right)$

$-9\left(a-2\right)-7\left(4a-b\right)$

$f\left(x\right)=2x^2+10x+12$

$\lim_{a\to0}\left(\frac{\left(x+a\right)^{x+a}-x^x}{a}\right)$

$5\left(3^n-2^n\right)-6\left(3^{n-1}-2^{n-1}\right)$