1. **Problem statement:** We are given the graph of the first derivative $f'$ of a continuous function $f$ on $\mathbb{R}$. We need to identify which statement among (a), (b), (c), and (d) is wrong.
2. **Recall key concepts:**
- A critical point of $f$ occurs where $f'(x) = 0$ or $f'(x)$ is undefined.
- An inflection point of $f$ occurs where the concavity changes, i.e., where $f''(x)$ changes sign.
- The convexity (concavity) of $f$ is determined by the sign of $f''(x)$: if $f''(x) > 0$, $f$ is convex up; if $f''(x) < 0$, $f$ is convex down.
3. **Analyze the graph of $f'$:**
- The graph of $f'$ is symmetric around the y-axis and sharply rises near $x=0$.
- At $x=0$, $f'(0) = 0$ because the curve touches the x-axis.
4. **Check each statement:**
(a) "The function $f$ has an inflection point at $x=0$":
- Inflection points occur where $f''$ changes sign.
- Since $f'$ has a minimum at $x=0$ (sharp rise on both sides), $f''(0) = 0$ and $f''$ changes from negative to positive or vice versa.
- So, (a) is true.
(b) "The curve of $f$ is convex up on $]-\infty,0[$":
- Convex up means $f''(x) > 0$.
- Since $f'$ is decreasing on $]-\infty,0[$ (curve goes down to 0), $f''(x) = f'(x)' < 0$ there.
- So $f$ is convex down on $]-\infty,0[$, not convex up.
- Therefore, (b) is false.
(c) "The function $f$ has a critical point at $x=0$":
- Since $f'(0) = 0$, $x=0$ is a critical point.
- So, (c) is true.
(d) "The curve of $f$ is convex up on $]0,\infty[$":
- For $x>0$, $f'$ is increasing (curve rises sharply), so $f''(x) > 0$.
- Hence, $f$ is convex up on $]0,\infty[$.
- So, (d) is true.
5. **Conclusion:** The wrong statement is (b).
**Final answer:** (b) The curve of the function $f$ is convex up on the interval $]-\infty,0[$ is wrong.
Derivative Curve F13853
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