$\lim_{x\to\infty}\frac{\left(x^2-x+1\right)\left(x^2-x-1\right)}{2x\left(1-x^3\right)}$

$\left(6a-3b+c\right)^2$

$2\left(x+5\right)-7$

$12+\left(-7\right)-\left(-10\right)+6$

$\lim_{x\to\infty}\frac{\frac{10}{11}^x}{\frac{9}{10}^x+\frac{11}{12}^x}$

$-3\cdot3\cdot1\cdot\left(-4\right)$

$\lim_{x\to-5}\left(\frac{x^2+9x+20}{40-3x+x^2}\right)$