$$\frac{6}{x^2-x-6}-\frac{4}{x^2-2x-3}$$

$$\frac{2x-1}{x+3}+1\le0$$

$$\lim_{x\to a}t$$

$$sin^2\left(x\right)tan^2\left(x\right)-tan^2\left(x\right)$$

$$-5-3+5-7+7+3-9+4$$

$$x+121-163$$

$$\ln\left(3xy\right)=x+x^2$$