$$\frac{1}{\left(x^2\left(\sqrt{x^2-4}\right)\right)}$$

$$\left(x-5\right)^2\ge0$$

$$3secx-tanx$$

$$6x^2+19x+26=9x^2+34x+44$$

$$\int\frac{\sqrt{x}}{x-81}dx$$

$$\int x^7\left(x^8+256\right)^2dx$$

$$\frac{6x^4-41x^2+3x+6}{2x^2-4x\:-3\:}$$