1. **State the problem:** Convert the quadratic function $y = -\frac{1}{2}(x + 6)^2 + 2$ into vertex form, zero form, and standard form. Find the vertex coordinates, zeros, max/min, axis of symmetry, optimal value, y-intercept, and step pattern.
2. **Identify vertex form:** The given function is already in vertex form:
$$y = a(x - h)^2 + k$$
where $a = -\frac{1}{2}$, $h = -6$, and $k = 2$.
3. **Vertex coordinates:** The vertex is at $(h, k) = (-6, 2)$.
4. **Axis of symmetry:** The axis of symmetry is the vertical line $x = h = -6$.
5. **Max or min:** Since $a = -\frac{1}{2} < 0$, the parabola opens downward, so the vertex is a maximum point.
6. **Optimal value:** The maximum value of $y$ is the $y$-coordinate of the vertex, which is $2$.
7. **Convert to standard form:** Expand the vertex form:
$$y = -\frac{1}{2}(x + 6)^2 + 2 = -\frac{1}{2}(x^2 + 12x + 36) + 2$$
$$= -\frac{1}{2}x^2 - 6x - 18 + 2$$
$$= -\frac{1}{2}x^2 - 6x - 16$$
8. **Convert to zero form (factored form):** Set $y=0$ and solve for $x$:
$$0 = -\frac{1}{2}(x + 6)^2 + 2$$
$$\frac{1}{2}(x + 6)^2 = 2$$
$$ (x + 6)^2 = 4$$
$$x + 6 = \pm 2$$
So zeros are:
$$x = -6 + 2 = -4$$
$$x = -6 - 2 = -8$$
Zero form:
$$y = -\frac{1}{2}(x + 4)(x + 8)$$
9. **Y-intercept:** Set $x=0$ in standard form:
$$y = -\frac{1}{2}(0)^2 - 6(0) - 16 = -16$$
So the y-intercept is $(0, -16)$.
10. **Step pattern:** Since $a = -\frac{1}{2}$, the parabola opens downward and the step pattern from the vertex is:
- Move 1 unit right or left in $x$, $y$ changes by $-\frac{1}{2} \times 1^2 = -\frac{1}{2}$
- Move 2 units right or left in $x$, $y$ changes by $-\frac{1}{2} \times 2^2 = -2$
- Move 3 units right or left in $x$, $y$ changes by $-\frac{1}{2} \times 3^2 = -\frac{9}{2} = -4.5$
This means from the vertex at $(-6, 2)$, the points go down by these amounts as you move horizontally.
**Final answers:**
- Vertex form: $y = -\frac{1}{2}(x + 6)^2 + 2$
- Standard form: $y = -\frac{1}{2}x^2 - 6x - 16$
- Zero form: $y = -\frac{1}{2}(x + 4)(x + 8)$
- Vertex: $(-6, 2)$
- Zeros: $x = -8, -4$
- Max value: $2$ at $x = -6$
- Axis of symmetry: $x = -6$
- Y-intercept: $(0, -16)$
- Step pattern: down $\frac{1}{2}$, down $2$, down $4.5$ for steps 1, 2, 3 from vertex
Quadratic Forms 694Ae3
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