$$\left(x+1\right)\left(x-1\right)+\left(3+x\left(3-x\right)\right)$$

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

$$1^{18}-9^2$$

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

$$\lim_{x\to1.5}\left(\sin\left(1.01\right)+1\right)$$

$$sex\left(0\right)$$