Limit Infinity A83F57
1. **State the problem:** We need to find the limit as $x$ approaches $+\infty$ of the expression $\left(\sqrt{x^2 + 2} - x\right)^5$.
2. **Recall the formula and approach:** When dealing with limits involving expressions like $\sqrt{x^2 + a} - x$ as $x \to +\infty$, it is useful to rationalize the expression to simplify it.
3. **Rationalize the inner expression:**
$$\sqrt{x^2 + 2} - x = \frac{(\sqrt{x^2 + 2} - x)(\sqrt{x^2 + 2} + x)}{\sqrt{x^2 + 2} + x} = \frac{x^2 + 2 - x^2}{\sqrt{x^2 + 2} + x} = \frac{2}{\sqrt{x^2 + 2} + x}$$
4. **Simplify the denominator for large $x$:**
As $x \to +\infty$, $\sqrt{x^2 + 2} = x\sqrt{1 + \frac{2}{x^2}} \approx x\left(1 + \frac{1}{2} \cdot \frac{2}{x^2}\right) = x + \frac{1}{x}$.
So,
$$\sqrt{x^2 + 2} + x \approx x + \frac{1}{x} + x = 2x + \frac{1}{x}$$
5. **Evaluate the inner expression limit:**
$$\frac{2}{2x + \frac{1}{x}} = \frac{2}{2x + \frac{1}{x}} = \frac{2}{2x} \text{ as } x \to +\infty \text{ since } \frac{1}{x} \to 0$$
Thus,
$$\sqrt{x^2 + 2} - x \approx \frac{2}{2x} = \frac{1}{x}$$
6. **Raise to the fifth power:**
$$\left(\sqrt{x^2 + 2} - x\right)^5 \approx \left(\frac{1}{x}\right)^5 = \frac{1}{x^5}$$
7. **Find the limit:**
As $x \to +\infty$, $\frac{1}{x^5} \to 0$.
**Final answer:**
$$\lim_{x \to +\infty} \left(\sqrt{x^2 + 2} - x\right)^5 = 0$$