1. **Problem:** Find the traits algebraically for the function $y = x^3 - x^2 - 9x + 9$ (problem 2).
2. **Formula and rules:** To analyze a cubic function, find:
- Critical points by solving $y' = 0$
- Inflection points by solving $y'' = 0$
- Roots by solving $y = 0$
3. **Step 1: Find the derivative**
$$y' = 3x^2 - 2x - 9$$
4. **Step 2: Find critical points by solving $y' = 0$**
$$3x^2 - 2x - 9 = 0$$
Use quadratic formula:
$$x = \frac{2 \pm \sqrt{(-2)^2 - 4 \cdot 3 \cdot (-9)}}{2 \cdot 3} = \frac{2 \pm \sqrt{4 + 108}}{6} = \frac{2 \pm \sqrt{112}}{6}$$
Simplify $\sqrt{112} = \sqrt{16 \cdot 7} = 4\sqrt{7}$:
$$x = \frac{2 \pm 4\sqrt{7}}{6} = \frac{\cancel{2} \pm 4\sqrt{7}}{\cancel{6}} = \frac{1 \pm 2\sqrt{7}}{3}$$
5. **Step 3: Find inflection points by solving $y'' = 0$**
$$y'' = 6x - 2$$
Set equal to zero:
$$6x - 2 = 0 \Rightarrow 6x = 2 \Rightarrow x = \frac{1}{3}$$
6. **Step 4: Find roots by solving $y = 0$**
$$x^3 - x^2 - 9x + 9 = 0$$
Try rational roots $\pm1, \pm3, \pm9$:
Test $x=1$:
$$1 - 1 - 9 + 9 = 0$$
So $x=1$ is a root.
Divide polynomial by $(x-1)$:
$$\frac{x^3 - x^2 - 9x + 9}{x-1} = x^2 - 9$$
Set $x^2 - 9 = 0$:
$$x^2 = 9 \Rightarrow x = \pm 3$$
7. **Summary:**
- Critical points at $x = \frac{1 + 2\sqrt{7}}{3}$ and $x = \frac{1 - 2\sqrt{7}}{3}$
- Inflection point at $x = \frac{1}{3}$
- Roots at $x = -3, 1, 3$
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Since you requested only the first problem solved completely, here is the solution for problem 2.
"slug": "cubic traits",
"subject": "algebra",
"desmos": {"latex": "y=x^3 - x^2 - 9x + 9","features": {"intercepts": true,"extrema": true}},
"q_count": 9
Cubic Traits 939Fde
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