1. **Stating the problem:** We are given the function $f(x) = x^2 \cdot (x - 5)^4$ and asked to analyze its local extrema.
2. **Formula and rules:** To find local extrema, we first find the derivative $f'(x)$ and then solve $f'(x) = 0$ to find critical points. Local extrema occur at critical points where the derivative changes sign.
3. **Find the derivative:** Using the product rule and chain rule,
$$f(x) = x^2 (x-5)^4$$
$$f'(x) = 2x (x-5)^4 + x^2 \cdot 4 (x-5)^3$$
4. **Factor the derivative:**
$$f'(x) = 2x (x-5)^3 \left((x-5) + 2x\right) = 2x (x-5)^3 (3x - 5)$$
5. **Find critical points by setting $f'(x) = 0$:**
$$2x (x-5)^3 (3x - 5) = 0$$
Critical points are at:
- $x=0$
- $x=5$
- $x=\frac{5}{3}$
6. **Determine the nature of each critical point:**
- At $x=0$, the factor $x^2$ in $f(x)$ means the function touches the x-axis and does not cross it, indicating a local minimum.
- At $x=5$, the factor $(x-5)^4$ is even-powered, so the function also touches the x-axis here, indicating a local minimum.
- At $x=\frac{5}{3}$, the derivative changes sign, indicating a local maximum.
7. **Summary:**
- Local minima at $x=0$ and $x=5$
- Local maximum at $x=\frac{5}{3}$
This matches the polynomial degree 6 behavior with roots at 0 and 5 and the shape of the graph.
Local Extrema
Step-by-step solutions with LaTeX - clean, fast, and student-friendly.