1. **Problem 16:** Write $y = x^2 - 8x + 12$ in vertex form, identify axis of symmetry, extrema, and zeros.
2. **Formula:** Vertex form is $y = a(x-h)^2 + k$ where $(h,k)$ is the vertex.
3. **Complete the square:**
$$y = x^2 - 8x + 12 = (x^2 - 8x + 16) - 16 + 12 = (x - 4)^2 - 4$$
4. **Vertex:** $(4, -4)$, axis of symmetry: $x = 4$.
5. **Extrema:** Since $a=1 > 0$, parabola opens upward, vertex is minimum point at $y = -4$.
6. **Zeros:** Solve $0 = (x - 4)^2 - 4$:
$$ (x - 4)^2 = 4 $$
$$ x - 4 = \pm 2 $$
$$ x = 4 \pm 2 $$
Zeros: $x=2$ and $x=6$.
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7. **Problem 17:** Write $y = -x^2 - 2x + 3$ in vertex form, identify axis of symmetry, extrema, and zeros.
8. **Complete the square:**
$$y = -(x^2 + 2x) + 3 = -\left(x^2 + 2x + 1\right) + 3 + 1 = -(x + 1)^2 + 4$$
9. **Vertex:** $(-1, 4)$, axis of symmetry: $x = -1$.
10. **Extrema:** Since $a = -1 < 0$, parabola opens downward, vertex is maximum point at $y = 4$.
11. **Zeros:** Solve $0 = -(x + 1)^2 + 4$:
$$ (x + 1)^2 = 4 $$
$$ x + 1 = \pm 2 $$
$$ x = -1 \pm 2 $$
Zeros: $x = -3$ and $x = 1$.
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**Summary:**
- Equation 16 vertex form: $y = (x - 4)^2 - 4$
- Axis of symmetry: $x=4$
- Minimum at $(4, -4)$
- Zeros at $x=2, 6$
- Equation 17 vertex form: $y = -(x + 1)^2 + 4$
- Axis of symmetry: $x=-1$
- Maximum at $(-1, 4)$
- Zeros at $x=-3, 1$
Vertex Form Parabolas 447B03
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