$$\left(x-6\right)\left(x-11\right)$$

$$\lim_{x\to2}\frac{x^2-x-1}{\left|x-2\right|}$$

$$\left(e-1\right)\left(e+2\right)^2-\left(e-1\right)^2\left(e+2\right)$$

$$\frac{dy}{dx}=\frac{xy^2}{\sqrt{3+x^2}}$$

$$15^{-4}\cdot15^6$$

$$x^2-14x+14$$

$$\frac{x^4-1}{x^3+x^2+x+1}$$