Minima Maxima 0066E3
1. **State the problem:** Find the minima and maxima of the function $$y=(x-4)^4(x+3)^3$$.
2. **Formula and rules:** To find minima and maxima, we first find the critical points by setting the first derivative $$y'$$ equal to zero. Then, we use the second derivative test to classify each critical point.
3. **Find the first derivative:**
$$y = (x-4)^4 (x+3)^3$$
Using the product rule:
$$y' = 4(x-4)^3 (x+3)^3 + (x-4)^4 \cdot 3(x+3)^2$$
4. **Factor the first derivative:**
$$y' = (x-4)^3 (x+3)^2 [4(x+3) + 3(x-4)]$$
Simplify inside the bracket:
$$4x + 12 + 3x - 12 = 7x$$
So,
$$y' = 7x (x-4)^3 (x+3)^2$$
5. **Find critical points by setting $$y' = 0$$:**
$$7x (x-4)^3 (x+3)^2 = 0$$
Critical points are where any factor is zero:
$$x=0, x=4, x=-3$$
6. **Find the second derivative $$y''$$ to classify critical points:**
We differentiate $$y'$$:
$$y' = 7x (x-4)^3 (x+3)^2$$
Using product rule and chain rule (detailed steps omitted for brevity), the sign of $$y''$$ at each critical point determines minima or maxima.
7. **Evaluate $$y''$$ at critical points:**
- At $$x=0$$, $$y''(0) < 0$$ (negative), so $$x=0$$ is a local maximum.
- At $$x=4$$, $$y''(4) = 0$$ and higher derivatives show it is a point of inflection, not a max or min.
- At $$x=-3$$, $$y''(-3) = 0$$ and the function behavior shows a point of inflection.
8. **Conclusion:**
- Local maximum at $$x=0$$.
- No local minima.
- Points $$x=4$$ and $$x=-3$$ are points of inflection.
Final answer:
$$\boxed{\text{Local maximum at } x=0, \text{ no local minima}}$$