1. **State the problem:** We are given the function $f(x) = -\frac{1}{30}(x+3)(x-27)$ and want to understand its properties.
2. **Formula and rules:** This is a quadratic function in factored form. The zeros (roots) occur where each factor equals zero: $x+3=0$ or $x-27=0$.
3. **Find the roots:**
$$x+3=0 \implies x=-3$$
$$x-27=0 \implies x=27$$
4. **Expand the function:**
$$f(x) = -\frac{1}{30}(x+3)(x-27) = -\frac{1}{30}(x^2 - 27x + 3x - 81) = -\frac{1}{30}(x^2 - 24x - 81)$$
5. **Distribute the coefficient:**
$$f(x) = -\frac{1}{30}x^2 + \frac{24}{30}x + \frac{81}{30} = -\frac{1}{30}x^2 + \frac{4}{5}x + \frac{27}{10}$$
6. **Find the vertex:** The vertex of a quadratic $ax^2 + bx + c$ is at $x = -\frac{b}{2a}$.
Here, $a = -\frac{1}{30}$ and $b = \frac{4}{5}$.
Calculate:
$$x = -\frac{\frac{4}{5}}{2 \times -\frac{1}{30}} = -\frac{\frac{4}{5}}{-\frac{2}{30}} = -\frac{\frac{4}{5}}{-\frac{1}{15}} = -\frac{4}{5} \times -15 = 12$$
7. **Find the vertex's y-coordinate:**
$$f(12) = -\frac{1}{30}(12+3)(12-27) = -\frac{1}{30}(15)(-15) = -\frac{1}{30} \times -225 = 7.5$$
8. **Summary:**
- Roots at $x = -3$ and $x = 27$
- Vertex at $(12, 7.5)$
- Parabola opens downward (since $a < 0$)
**Final answer:** The function $f(x) = -\frac{1}{30}(x+3)(x-27)$ has roots at $x = -3$ and $x = 27$, and a vertex at $(12, 7.5)$ with the parabola opening downward.
Quadratic Factors 3Fa761
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