1. **State the problem:** Find the limits of the function $$f(x) = \sqrt{x^2 + 5x - x}$$ as $$x \to \infty$$ and $$x \to -\infty$$.
2. **Simplify the function inside the square root:**
$$x^2 + 5x - x = x^2 + 4x$$
So,
$$f(x) = \sqrt{x^2 + 4x}$$.
3. **Factor inside the square root to analyze behavior:**
$$f(x) = \sqrt{x^2 + 4x} = \sqrt{x^2(1 + \frac{4}{x})} = \sqrt{x^2} \sqrt{1 + \frac{4}{x}}$$.
4. **Recall that $$\sqrt{x^2} = |x|$$, so:**
$$f(x) = |x| \sqrt{1 + \frac{4}{x}}$$.
5. **Analyze the limit as $$x \to \infty$$:**
- When $$x \to \infty$$, $$|x| = x$$.
- Also, $$\lim_{x \to \infty} \sqrt{1 + \frac{4}{x}} = \sqrt{1 + 0} = 1$$.
Therefore,
$$\lim_{x \to \infty} f(x) = \lim_{x \to \infty} x \cdot 1 = \infty$$.
6. **Analyze the limit as $$x \to -\infty$$:**
- When $$x \to -\infty$$, $$|x| = -x$$ (since $$x$$ is negative, absolute value is $$-x$$).
- Also, $$\lim_{x \to -\infty} \sqrt{1 + \frac{4}{x}} = 1$$.
Therefore,
$$\lim_{x \to -\infty} f(x) = \lim_{x \to -\infty} (-x) \cdot 1 = \infty$$.
7. **Final answer:**
$$\lim_{x \to \infty} f(x) = \infty$$ and $$\lim_{x \to -\infty} f(x) = \infty$$.
This matches the first option given.
Limit Infinity 72A4B5
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