Mean Value Points
1. **Problem Statement:**
We are given a function $f$ defined on the interval $[a,b]$ with $f(b) > f(a)$ and $a \leq x \leq b$. The derivative $f'(x)$ exists for all $x$ in $(a,b)$ except at $x=0$. We want to find the number of values $c$ in $(a,b)$ such that
$$\lim_{x \to c} \frac{f(x) - f(c)}{x - c} = \frac{f(b) - f(a)}{b - a}.$$
This limit is the definition of the derivative at $c$, so we are looking for points where the instantaneous rate of change equals the average rate of change over $[a,b]$.
2. **Relevant Theorem:**
This is a direct application of the **Mean Value Theorem (MVT)** which states:
If $f$ is continuous on $[a,b]$ and differentiable on $(a,b)$, then there exists at least one $c \in (a,b)$ such that
$$f'(c) = \frac{f(b) - f(a)}{b - a}.$$
3. **Important Notes:**
- The function $f$ is continuous on $[a,b]$.
- The derivative exists everywhere on $(a,b)$ except at $x=0$.
- The MVT requires differentiability on the open interval, but here $f'(0)$ does not exist.
4. **Implication of the derivative not existing at $x=0$:**
Since $f'(0)$ does not exist, the MVT does not guarantee a single $c$ but the problem asks for the number of $c$ where the derivative (or the limit defining it) equals the average rate of change.
5. **Analyzing the graph and behavior:**
- The graph dips below the x-axis near zero, indicating a cusp or corner at $x=0$ where derivative fails.
- The function has a local maximum and a local minimum in $(a,b)$.
- The average slope $\frac{f(b)-f(a)}{b-a}$ is positive since $f(b) > f(a)$.
6. **Number of points where the slope equals the average slope:**
- The graph crosses the average slope line multiple times.
- Because of the cusp at $x=0$, the function can have multiple points where the secant slope equals the instantaneous slope.
- By the shape described, there are **four** such points.
7. **Conclusion:**
The number of values $c$ in $(a,b)$ such that
$$\lim_{x \to c} \frac{f(x) - f(c)}{x - c} = \frac{f(b) - f(a)}{b - a}$$
is **four**.
**Final answer:** (D) Four