$$2\:cot\:x\:+\:tan\:x\:+1$$

$$\lim_{x\to-1}\left(5x^2+2\right)\:\left(x^2+1\right)$$

$$f\left(x\right)=x^3-\frac{1}{x^3}$$

$$\frac{dy}{dx}=x+7y$$

$$\frac{1}{4}x^2y^2+\frac{7}{8}x+8x+8^4+\frac{3}{8}x^2y^2-9x$$

$$-4x+8-x$$