Question: Select the correct answer.
Consider function $f$.
$$f(x)=\begin{cases} 2x, & x<0 \\ -x^2 - 4x + 1, & 02 \end{cases}$$
Which statement is true about function $f$?
The function is increasing over its entire domain.
As $x$ approaches positive infinity, $f(x)$ approaches positive infinity.
The domain is all real numbers.
The function is continuous.
1. **State the problem:** We are given a piecewise function
$$f(x)=\begin{cases} 2x, & x<0 \\ -x^2 - 4x + 1, & 02 \end{cases}$$
and need to determine which of the given statements about $f$ is true.
2. **Analyze the domain:** The function is defined for $x<0$, $02$. Notice that $x=0$ and $x=2$ are not included in the domain because the function pieces are strict inequalities.
- Therefore, the domain is $(-\infty,0) \cup (0,2) \cup (2,\infty)$.
- This means the domain is **not all real numbers** because $x=0$ and $x=2$ are excluded.
3. **Check if the function is increasing over its entire domain:**
- For $x<0$, $f(x)=2x$ which is a linear function with slope $2>0$, so it is increasing on $(-\infty,0)$.
- For $02$, $f(x)=\frac{1}{2}x + 3$, which is linear with positive slope $\frac{1}{2}$, so increasing on $(2,\infty)$.
- Since $f$ decreases on $(0,2)$, it is **not increasing over its entire domain**.
4. **Check behavior as $x \to +\infty$:**
- For $x>2$, $f(x) = \frac{1}{2}x + 3$.
- As $x \to +\infty$, $f(x) \to +\infty$ because the linear term dominates.
5. **Check continuity:**
- At $x=0$, the function is not defined, so it cannot be continuous there.
- At $x=2$, the function is not defined, so it cannot be continuous there.
- Therefore, $f$ is **not continuous** on its entire domain.
**Summary of statements:**
- "The function is increasing over its entire domain." — False.
- "As $x$ approaches positive infinity, $f(x)$ approaches positive infinity." — True.
- "The domain is all real numbers." — False.
- "The function is continuous." — False.
**Final answer:** The true statement is:
**As $x$ approaches positive infinity, $f(x)$ approaches positive infinity.**