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

$$\frac{dy}{dx}=\frac{xy^2}{x^2+1}\:;y\left(0\right)=-9$$

$$\frac{12}{11x+2}<8$$

$$\frac{d^2}{dx^2}\left(-\frac{1}{3}x^{-3}+\frac{1}{6}x^{-2}-x^4\right)$$

$$\lim_{h\to0}\left(\frac{eh-1}{h}\right)$$

$$\lim_{x\to\infty}\left(ln\left(3x\right)-ln\left(x+9\right)\right)$$

$$-2\cot^2\left(x\right)=\frac{1}{\sec\left(x\right)+1}-\frac{1}{\sec\:\left(x\right)+1}$$