$$\int fe^xdf$$

$$2x-50<4x-800$$

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

$$sen^4r\:-\:cos^4r\:=sen^2r\:-cos^2r$$

$$\int e^{-\frac{x}{3}}sen\left(2x\right)dx$$

$$x^4+4x^3-5x^2$$

$$\frac{2x^3}{8x^2}$$