1. **Problem:** Identify characteristics of the quadratic function $f(x) = -(x + 6)(x + 2)$.
2. **Step 1: Expand the function**
$$f(x) = -(x + 6)(x + 2) = -(x^2 + 2x + 6x + 12) = -(x^2 + 8x + 12) = -x^2 - 8x - 12$$
3. **Step 2: Find the vertex**
The vertex form is $f(x) = a(x - h)^2 + k$ where $(h,k)$ is the vertex.
Use vertex formula $h = -\frac{b}{2a}$ for $ax^2 + bx + c$.
Here, $a = -1$, $b = -8$.
$$h = -\frac{-8}{2(-1)} = \frac{8}{-2} = -4$$
Calculate $k = f(-4)$:
$$k = -(-4)^2 - 8(-4) - 12 = -16 + 32 - 12 = 4$$
Vertex is $(-4, 4)$.
4. **Step 3: Axis of symmetry**
Axis of symmetry is the vertical line through the vertex:
$$x = -4$$
5. **Step 4: Domain**
Quadratic functions have domain all real numbers:
$$\text{Domain}: (-\infty, \infty)$$
6. **Step 5: Range**
Since $a = -1 < 0$, parabola opens downward, so maximum at vertex $y=4$.
$$\text{Range}: (-\infty, 4]$$
7. **Step 6: Increasing and decreasing intervals**
- Increasing on $(-\infty, -4)$
- Decreasing on $(-4, \infty)$
8. **Step 7: End behavior**
As $x \to -\infty$, $y \to -\infty$ (because of negative leading coefficient)
As $x \to +\infty$, $y \to -\infty$
**Final answers:**
- Vertex: $(-4, 4)$
- Axis of Symmetry: $x = -4$
- Domain: $(-\infty, \infty)$
- Range: $(-\infty, 4]$
- Increasing: $(-\infty, -4)$
- Decreasing: $(-4, \infty)$
- End Behavior: $y \to -\infty$ as $x \to -\infty$ and $y \to -\infty$ as $x \to +\infty$
Quadratic Characteristics 4417D4
Step-by-step solutions with LaTeX - clean, fast, and student-friendly.