Analyze Cubic Da531D
1. Problem: Analyze the function $$y = \frac{x^3}{3} - \frac{x^2}{2} - 2x + \frac{1}{3}$$ to find local maxima, minima, inflection points, and intervals of concavity.
2. Find the first derivative:
$$y' = x^2 - x - 2$$
3. Solve $$y' = 0$$ for critical points:
$$x^2 - x - 2 = 0 \implies (x-2)(x+1) = 0 \implies x=2, x=-1$$
4. Find the second derivative:
$$y'' = 2x - 1$$
5. Evaluate $$y''$$ at critical points:
- At $$x=2$$: $$y''(2) = 3 > 0$$, local minimum.
- At $$x=-1$$: $$y''(-1) = -3 < 0$$, local maximum.
6. Find inflection points by solving $$y''=0$$:
$$2x - 1 = 0 \implies x=\frac{1}{2}$$
7. Determine concavity intervals:
- Concave up where $$y'' > 0$$: $$x > \frac{1}{2}$$
- Concave down where $$y'' < 0$$: $$x < \frac{1}{2}$$
8. Calculate function values at critical and inflection points:
- $$y(2) = \frac{8}{3} - 2 - 4 + \frac{1}{3} = -\frac{1}{3}$$
- $$y(-1) = -\frac{1}{3} - \frac{1}{2} + 2 + \frac{1}{3} = \frac{3}{2}$$
- $$y\left(\frac{1}{2}\right) = \frac{1}{24} - \frac{1}{8} - 1 + \frac{1}{3} = -\frac{7}{24}$$
Final answer:
- Local maximum at $$(-1, \frac{3}{2})$$
- Local minimum at $$(2, -\frac{1}{3})$$
- Inflection point at $$\left(\frac{1}{2}, -\frac{7}{24}\right)$$
- Concave down on $$(-\infty, \frac{1}{2})$$
- Concave up on $$\left(\frac{1}{2}, \infty\right)$$