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

$$4x^2-9y^2=36$$

$$423.4\cdot25$$

$$\lim_{x\to1}\left(\frac{1-x+x\log x}{\left(x-1\right)}\right)$$

$$\frac{5x-3}{x}-\frac{7-x}{x+2}$$

$$7k-6k-2-9$$

$$2x+1\ge0$$