1. **Problem Statement:**
We are given the graph of the first derivative $f'(x)$ of a function $f(x)$, which is a parabola opening upwards with roots at $x=-1$ and $x=1$. We need to determine which of the given graphs (a, b, c, or d) could represent the original function $f(x)$.
2. **Understanding the derivative:**
The first derivative $f'(x)$ is zero at $x=-1$ and $x=1$, and positive or negative elsewhere depending on the parabola shape.
3. **Key formula and rules:**
- The roots of $f'(x)$ correspond to critical points (local maxima, minima, or inflection points) of $f(x)$.
- Since $f'(x)$ is a parabola opening upwards with roots at $-1$ and $1$, it can be expressed as:
$$f'(x) = a(x+1)(x-1) = a(x^2 - 1)$$
where $a > 0$ because it opens upwards.
4. **Sign analysis of $f'(x)$:**
- For $x < -1$, $f'(x) > 0$ (since both $(x+1)$ and $(x-1)$ are negative, their product is positive).
- For $-1 < x < 1$, $f'(x) < 0$ (one factor positive, one negative).
- For $x > 1$, $f'(x) > 0$.
5. **Implications for $f(x)$:**
- $f(x)$ is increasing when $f'(x) > 0$ and decreasing when $f'(x) < 0$.
- Therefore, $f(x)$ increases on $(-, -1)$, decreases on $(-1, 1)$, and increases again on $(1, )$.
- This means $f(x)$ has a local maximum at $x=-1$ and a local minimum at $x=1$.
6. **Checking the options:**
- (a) and (b) describe cubic-like functions with two turning points and three x-intercepts, consistent with local max and min.
- (c) describes a cubic-like function with a single minimum between 0 and 1, which does not match the critical points at $-1$ and $1$.
- (d) is a straight line, which cannot have a derivative that is a parabola.
7. **Conclusion:**
The function $f(x)$ must have two turning points at $x=-1$ and $x=1$, with a local maximum at $-1$ and a local minimum at $1$. Both (a) and (b) fit this description, but since the problem states the derivative is positive outside $[-1,1]$ and negative inside, the shape with a local max at $-1$ and local min at $1$ matches these options.
**Final answer:** The graphs labeled (a) and (b) could represent the general shape of $f(x)$ given the derivative $f'(x)$.
Derivative Shape 9A5D5A
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