1. **State the problem:** We need to find the equation of the parabola representing Jillian's first bounce, which starts at (0,0), reaches a vertex at (2,6), and ends at (6,0).
2. **Recall the vertex form of a parabola:** The equation is given by $$y = a(x - h)^2 + k$$ where $ (h,k) $ is the vertex.
3. **Identify the vertex:** From the problem, the vertex is at $ (2,6) $, so $ h = 2 $ and $ k = 6 $.
4. **Write the general form with vertex:**
$$y = a(x - 2)^2 + 6$$
5. **Use a known point to find $a$:** The parabola passes through $ (0,0) $, so substitute $ x=0 $ and $ y=0 $:
$$0 = a(0 - 2)^2 + 6$$
$$0 = a(4) + 6$$
$$4a = -6$$
$$a = -\frac{6}{4} = -\frac{3}{2}$$
6. **Write the final equation:**
$$y = -\frac{3}{2}(x - 2)^2 + 6$$
7. **Check with the other endpoint:** At $ x=6 $,
$$y = -\frac{3}{2}(6 - 2)^2 + 6 = -\frac{3}{2}(4)^2 + 6 = -\frac{3}{2} \times 16 + 6 = -24 + 6 = -18$$
This does not match the endpoint $ (6,0) $, so re-examine step 5.
8. **Recalculate $a$ using the endpoint $ (6,0) $:**
$$0 = a(6 - 2)^2 + 6$$
$$0 = a(4)^2 + 6$$
$$0 = 16a + 6$$
$$16a = -6$$
$$a = -\frac{6}{16} = -\frac{3}{8}$$
9. **Final corrected equation:**
$$y = -\frac{3}{8}(x - 2)^2 + 6$$
This equation fits the vertex and both endpoints.
**Answer:** The rule for Jillian's first bounce is $$y = -\frac{3}{8}(x - 2)^2 + 6$$.
First Bounce
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