1. **State the problem:** Analyze the quadratic function $f(x) = x^2 - 4x - 8$.
2. **Formula and rules:** A quadratic function is generally written as $f(x) = ax^2 + bx + c$.
- The graph is a parabola.
- If $a > 0$, the parabola opens upward (concave up).
- The vertex formula is $\left( -\frac{b}{2a}, f\left(-\frac{b}{2a}\right) \right)$.
- The y-intercept is at $(0, c)$.
3. **Identify coefficients:** Here, $a=1$, $b=-4$, and $c=-8$.
4. **Concavity:** Since $a=1 > 0$, the parabola opens upward (concave up).
5. **Find vertex:**
$$x_{vertex} = -\frac{b}{2a} = -\frac{-4}{2 \times 1} = \frac{4}{2} = 2$$
Evaluate $f(2)$:
$$f(2) = (2)^2 - 4(2) - 8 = 4 - 8 - 8 = -12$$
So, the vertex is at $(2, -12)$.
6. **Find y-intercept:**
At $x=0$:
$$f(0) = 0^2 - 4(0) - 8 = -8$$
So, the y-intercept is at $(0, -8)$.
7. **Summary:**
- The parabola opens upward.
- Vertex at $(2, -12)$.
- Y-intercept at $(0, -8)$.
This matches the given information and confirms the analysis.
Quadratic Analysis 7Be12D
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