1. **State the problem:** We are given the function $$f(x) = 8 - 2x - x^2$$ and need to find the coordinates of points a, b, and c on its graph.
2. **Understand the function:** This is a quadratic function in standard form $$f(x) = -x^2 - 2x + 8$$ which is a downward-opening parabola because the coefficient of $$x^2$$ is negative.
3. **Find the vertex (point c):** The vertex of a parabola $$y = ax^2 + bx + c$$ is at $$x = -\frac{b}{2a}$$.
Here, $$a = -1$$ and $$b = -2$$, so
$$x_c = -\frac{-2}{2 \times -1} = -\frac{-2}{-2} = -1$$.
4. **Calculate $$y$$ at vertex:**
$$f(-1) = 8 - 2(-1) - (-1)^2 = 8 + 2 - 1 = 9$$.
So, point c is $$(-1, 9)$$.
5. **Find point a:** Point a is on the positive y-axis above the vertex, so $$x=0$$.
Calculate $$f(0)$$:
$$f(0) = 8 - 2(0) - 0^2 = 8$$.
So, point a is $$(0, 8)$$.
6. **Find point b:** Point b is on the negative x-axis below the x-axis, so $$y=0$$ and $$x < 0$$.
Set $$f(x) = 0$$:
$$8 - 2x - x^2 = 0$$
Rewrite as:
$$-x^2 - 2x + 8 = 0$$
Multiply both sides by $$-1$$ to simplify:
$$\cancel{-}x^2 - 2x + 8 = 0 \Rightarrow x^2 + 2x - 8 = 0$$
7. **Solve quadratic equation:**
$$x = \frac{-2 \pm \sqrt{2^2 - 4 \times 1 \times (-8)}}{2 \times 1} = \frac{-2 \pm \sqrt{4 + 32}}{2} = \frac{-2 \pm \sqrt{36}}{2}$$
$$x = \frac{-2 \pm 6}{2}$$
Two solutions:
- $$x = \frac{-2 + 6}{2} = 2$$ (positive, discard since point b is on negative x-axis)
- $$x = \frac{-2 - 6}{2} = -4$$ (negative, valid)
8. **Find $$y$$ at $$x = -4$$:**
$$f(-4) = 8 - 2(-4) - (-4)^2 = 8 + 8 - 16 = 0$$
So, point b is $$(-4, 0)$$.
**Final answers:**
- Point a: $$(0, 8)$$
- Point b: $$(-4, 0)$$
- Point c: $$(-1, 9)$$
Parabola Points C0461F
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