$\left(6x^2-6x-6y\right)^2$

$\frac{8m^3+27n^3}{2m+3n}$

$10+8+9\cdot4$

$-5.\left(-1\right).\left(-6\right)$

$\lim_{x\to1}\left(\frac{x^2-3x}{x}\right)$

$\left(4b-5\right)\left(4b+5\right)-\left(4b-1\right)^2$

$\lim_{x\to-\infty}\left(\frac{\sqrt{7+4x^2}}{2x+5}\right)$