$$-\frac{10x^2}{x^3}$$

$$\lim_{x\to\infty}\left(\frac{7}{9+e^{2x}}\right)$$

$$\int_1^3\pi\left(x-1\right)dx$$

$$\frac{\sin^2\left(-x\right)-\cos^2\left(-x\right)}{\sin\left(-x\right)-\cos\left(-x\right)}$$

$$\frac{2x+1}{x-5}=2$$

$$\frac{d}{dx}z=3a^2$$

$$\left(1+\left(\frac{x}{n}\right)\right)^n$$