$$\frac{x^5-x^4+x^2-3}{x^2+1}$$

$$\:f^4+12f^2+3$$

$$ec^{-1}\sqrt{2}$$

$$\int\frac{6x^3+4x^2-20x-16}{x^2-4}dx$$

$$2\cos\left(x\right)+\frac{1}{2\sqrt{x^3}}$$

$$\frac{1}{cot^2x}=sec^2x-1$$

$$\left(e^xsen\:y\:-2\right)dx+\left(e^xcos\:y+2\right)dy=0$$