Question: the graph of the continuous function which satisfies all the following conditions.
$f''(x)<0$ if $x<-6$
$f''(-6)=0$
$f''(x)>0$ if $x>-6$
$f'(x)>0$ forall $x$
1. **Problem Statement:**
We are given a continuous function $f$ with the following conditions:
- The second derivative $f''(x)<0$ for $x<-6$.
- The second derivative $f''(-6)=0$.
- The second derivative $f''(x)>0$ for $x>-6$.
- The first derivative $f'(x)>0$ for all $x$.
2. **Understanding the conditions:**
- $f''(x)$ is the concavity indicator of $f$. When $f''(x)<0$, the graph is concave down.
- When $f''(x)>0$, the graph is concave up.
- At $x=-6$, $f''(-6)=0$ indicates a possible inflection point.
- $f'(x)>0$ means $f$ is strictly increasing everywhere.
3. **Implications:**
- Since $f''(x)$ changes from negative to positive at $x=-6$, the graph changes concavity from concave down to concave up at $x=-6$.
- The function $f$ is increasing everywhere, so the slope $f'(x)$ is always positive.
4. **Sketching the graph:**
- For $x<-6$, the graph is increasing and concave down.
- At $x=-6$, the concavity changes.
- For $x>-6$, the graph is increasing and concave up.
5. **Summary:**
The graph of $f$ is strictly increasing with an inflection point at $x=-6$ where the concavity changes from downwards to upwards.
**Final answer:** The function $f$ is strictly increasing everywhere with an inflection point at $x=-6$ where the concavity changes from concave down to concave up.