Cubic Rational
1. **Problem Statement:**
We analyze the function $$y = x^3 + \frac{3}{x}$$ to find its critical points, concavity, and points of inflection.
2. **Find the first derivative:**
$$y' = \frac{d}{dx}\left(x^3 + \frac{3}{x}\right) = 3x^2 - \frac{3}{x^2}$$
3. **Find critical points by setting $$y' = 0$$:**
$$3x^2 - \frac{3}{x^2} = 0 \implies 3x^2 = \frac{3}{x^2} \implies x^4 = 1 \implies x = \pm 1$$
4. **Evaluate $$y$$ at critical points:**
- At $$x = -1$$: $$y = (-1)^3 + \frac{3}{-1} = -1 - 3 = -4$$
- At $$x = 1$$: $$y = 1^3 + \frac{3}{1} = 1 + 3 = 4$$
5. **Determine concavity by finding the second derivative:**
$$y'' = \frac{d}{dx}\left(3x^2 - \frac{3}{x^2}\right) = 6x + \frac{6}{x^3}$$
6. **Analyze concavity intervals:**
- For $$x > 0$$, $$y'' = 6x + \frac{6}{x^3} > 0$$, so the graph is concave up on $$(0, \infty)$$.
- For $$x < 0$$, $$y'' = 6x + \frac{6}{x^3} < 0$$, so the graph is concave down on $$(-\infty, 0)$$.
7. **Points of inflection:**
Set $$y'' = 0$$:
$$6x + \frac{6}{x^3} = 0 \implies 6x = -\frac{6}{x^3} \implies 6x^4 = -6 \implies x^4 = -1$$
No real solutions, so no points of inflection.
**Final summary:**
- Local maximum at $$x = -1$$ with $$y = -4$$.
- Local minimum at $$x = 1$$ with $$y = 4$$.
- Concave down on $$(-\infty, 0)$$.
- Concave up on $$(0, \infty)$$.
- No points of inflection.
The function has a vertical asymptote at $$x=0$$ where it is undefined.