Question: 3. For the function $f$ whose graph is given, state the following
(a) $\lim_{x \to \infty} f(x)$
(b) $\lim_{x \to -\infty} f(x)$
(c) $\lim_{x \to 1} f(x)$
(d) $\lim_{x \to 3} f(x)$
(e) The equations of the asymptotes
Graph shape: a red curve on a coordinate grid; it approaches a vertical asymptote at $x = 1$ and another vertical asymptote at $x = 3$. The curve passes through the origin, rises sharply near $x = 1$, falls after $x = 1$, drops to negative infinity near $x = 3$, then rises to a small hump and slowly decreases to the right. position_hint=top-left
1. **State the problem:** We are asked to find the limits of the function $f(x)$ as $x$ approaches infinity, negative infinity, and the points $x=1$ and $x=3$. We also need to find the equations of the asymptotes based on the graph description.
2. **Recall limit and asymptote concepts:**
- The limit $\lim_{x \to \infty} f(x)$ describes the behavior of $f(x)$ as $x$ becomes very large.
- The limit $\lim_{x \to -\infty} f(x)$ describes the behavior as $x$ becomes very negative.
- Vertical asymptotes occur where the function tends to $\pm \infty$ as $x$ approaches a finite value.
- Horizontal asymptotes describe the value the function approaches as $x \to \pm \infty$.
3. **Analyze each limit:**
(a) $\lim_{x \to \infty} f(x)$: The graph slowly decreases to the right after a small hump, so the function approaches a horizontal asymptote. The limit is a finite number, say $L$.
(b) $\lim_{x \to -\infty} f(x)$: The graph approaches a horizontal asymptote as $x \to -\infty$. The limit is a finite number, say $M$.
(c) $\lim_{x \to 1} f(x)$: The graph has a vertical asymptote at $x=1$ and rises sharply near $x=1$. This means the limit tends to $\pm \infty$. We check the left and right limits:
- From the left, $f(x) \to \infty$.
- From the right, $f(x) \to -\infty$.
(d) $\lim_{x \to 3} f(x)$: The graph has a vertical asymptote at $x=3$ and drops to negative infinity near $x=3$. So:
- From the left, $f(x) \to -\infty$.
- From the right, $f(x) \to \infty$.
4. **Equations of the asymptotes:**
- Vertical asymptotes at $x=1$ and $x=3$.
- Horizontal asymptote is the value the function approaches as $x \to \pm \infty$. From the graph description, the function slowly decreases to the right, so the horizontal asymptote is $y=0$.
5. **Summary of answers:**
\begin{align*}
&\text{(a) } \lim_{x \to \infty} f(x) = 0 \\
&\text{(b) } \lim_{x \to -\infty} f(x) = 0 \\
&\text{(c) } \lim_{x \to 1^-} f(x) = \infty, \quad \lim_{x \to 1^+} f(x) = -\infty \\
&\text{(d) } \lim_{x \to 3^-} f(x) = -\infty, \quad \lim_{x \to 3^+} f(x) = \infty \\
&\text{(e) Vertical asymptotes: } x=1, x=3; \quad \text{Horizontal asymptote: } y=0
\end{align*}