Parabola Analysis 9524E5
1. **Stating the problem:**
We are given the quadratic function $$y = -\frac{1}{2}x^2 - x + 1$$ and need to analyze its properties.
2. **Formula and important rules:**
The general form of a quadratic function is $$y = ax^2 + bx + c$$ where:
- $$a$$ determines the direction of the parabola (upward if $$a > 0$$, downward if $$a < 0$$).
- $$b$$ affects the position of the vertex.
- $$c$$ is the y-intercept.
3. **Identify coefficients:**
From the given equation, $$a = -\frac{1}{2}$$, $$b = -1$$, and $$c = 1$$.
4. **Direction of the parabola:**
Since $$a = -\frac{1}{2} < 0$$, the parabola opens downward.
5. **Find the vertex:**
The x-coordinate of the vertex is given by $$x = -\frac{b}{2a}$$.
Calculate:
$$x = -\frac{-1}{2 \times -\frac{1}{2}} = -\frac{-1}{-1} = -1$$.
6. **Find the y-coordinate of the vertex:**
Substitute $$x = -1$$ into the equation:
$$y = -\frac{1}{2}(-1)^2 - (-1) + 1 = -\frac{1}{2} + 1 + 1 = 1.5$$.
7. **Vertex coordinates:**
The vertex is at $$(-1, 1.5)$$.
8. **Find y-intercept:**
Set $$x=0$$:
$$y = -\frac{1}{2}(0)^2 - 0 + 1 = 1$$.
So the y-intercept is at $$(0,1)$$.
9. **Find x-intercepts:**
Set $$y=0$$ and solve:
$$0 = -\frac{1}{2}x^2 - x + 1$$
Multiply both sides by $$-2$$ to clear fraction:
$$0 = x^2 + 2x - 2$$
Use quadratic formula:
$$x = \frac{-2 \pm \sqrt{(2)^2 - 4(1)(-2)}}{2(1)} = \frac{-2 \pm \sqrt{4 + 8}}{2} = \frac{-2 \pm \sqrt{12}}{2} = \frac{-2 \pm 2\sqrt{3}}{2} = -1 \pm \sqrt{3}$$
10. **Final answer:**
- Parabola opens downward.
- Vertex at $$(-1, 1.5)$$.
- Y-intercept at $$(0,1)$$.
- X-intercepts at $$x = -1 + \sqrt{3}$$ and $$x = -1 - \sqrt{3}$$.