Curve Sketching Cea2F6
1. **Problem Statement:**
We are given the function $$F(x) = x^3 - 6x^2 + 9x + 1$$ and need to analyze its behavior by finding derivatives, critical points, inflection points, intervals of increase/decrease, and concavity.
2. **First Derivative and Critical Points:**
The first derivative $$F'(x)$$ helps us find critical points where the slope is zero or undefined.
$$F'(x) = \frac{d}{dx}(x^3 - 6x^2 + 9x + 1) = 3x^2 - 12x + 9$$
Set $$F'(x) = 0$$ to find critical points:
$$3x^2 - 12x + 9 = 0$$
Divide both sides by 3:
$$x^2 - 4x + 3 = 0$$
Factor:
$$(x - 3)(x - 1) = 0$$
So, critical points are at $$x = 1$$ and $$x = 3$$.
3. **Second Derivative and Inflection Points:**
The second derivative $$F''(x)$$ tells us about concavity and inflection points.
$$F''(x) = \frac{d}{dx}(3x^2 - 12x + 9) = 6x - 12$$
Set $$F''(x) = 0$$ to find inflection points:
$$6x - 12 = 0 \implies x = 2$$
4. **Intervals of Increase and Decrease:**
- For $$x < 1$$, pick $$x=0$$: $$F'(0) = 3(0)^2 - 12(0) + 9 = 9 > 0$$, so increasing.
- For $$1 < x < 3$$, pick $$x=2$$: $$F'(2) = 3(4) - 24 + 9 = 12 - 24 + 9 = -3 < 0$$, so decreasing.
- For $$x > 3$$, pick $$x=4$$: $$F'(4) = 3(16) - 48 + 9 = 48 - 48 + 9 = 9 > 0$$, so increasing.
5. **Intervals of Concavity:**
- For $$x < 2$$, pick $$x=0$$: $$F''(0) = 6(0) - 12 = -12 < 0$$, so concave down.
- For $$x > 2$$, pick $$x=3$$: $$F''(3) = 18 - 12 = 6 > 0$$, so concave up.
6. **Summary:**
- Critical points at $$x=1$$ and $$x=3$$.
- Inflection point at $$x=2$$.
- Increasing on $$(-\infty, 1) \cup (3, \infty)$$.
- Decreasing on $$(1, 3)$$.
- Concave down on $$(-\infty, 2)$$.
- Concave up on $$(2, \infty)$$.
7. **Final function for graphing:**
$$F(x) = x^3 - 6x^2 + 9x + 1$$