The vertex of a parabola that opens downward is at [tex]\((0,4)\)[/tex]. The vertex of a second parabola is at [tex]\((0,-4)\)[/tex]. If the parabolas intersect at two points, which statement must be true?

A. The second parabola opens downward.
B. The second parabola opens upward.
C. The points of intersection are on the [tex]\(x\)[/tex]-axis.
D. The points of intersection are of equal distance from the [tex]\(y\)[/tex]-axis.



Answer :

To solve this problem, let's analyze the given information step by step.

1. Understand the Vertices and Orientation of Parabolas:
- The first parabola has a vertex at [tex]\((0, 4)\)[/tex] and it opens downward. This means its maximum point is at [tex]\((0, 4)\)[/tex] and from there it curves downward.
- The second parabola has a vertex at [tex]\((0, -4)\)[/tex]. The direction in which this parabola opens will affect how and where it intersects with the first parabola.

2. Intersection Points:
- For the two parabolas to intersect at two points, the curves must cross each other. Given that the first parabola opens downward and has its vertex at [tex]\((0, 4)\)[/tex], any downward opening curve from [tex]\((0, -4)\)[/tex] would move further down and thus, would not intersect the first parabola again.
- Therefore, for the second parabola to intersect the first one, it must open upward. This setup ensures the parabolas will meet at two points - one point above and one point below the x-axis.

3. Symmetrical Intersection:
- The points of intersection will be symmetrically located with respect to the y-axis because both vertices lie on the y-axis ([tex]\(x=0\)[/tex]). This symmetry about the y-axis implies that the parabola's shapes will create points of intersection at equal distances to either side of the y-axis.

4. Drawing Conclusions about Intersection:
- The first parabola opens downward.
- The second parabola needs to open upward to ensure that they intersect at exactly two points.
- The points of intersection will be symmetrical relative to the y-axis due to the symmetry in the vertex locations.

Now, let's address the given statements:
1. "The second parabola opens downward."
- This is false. If the second parabola also opened downward, they would not intersect at two points.
2. "The second parabola opens upward."
- This is true. For them to intersect at two points, the second parabola must open upward.
3. "The points of intersection are on the x-axis."
- This is false. While it's possible for parabolas to intersect the x-axis, for this specific arrangement relative to their vertices, the points of intersection are not necessarily on the x-axis.
4. "The points of intersection are of equal distance from the y-axis."
- This is true. Given the symmetry around the y-axis, the points where the two parabolas intersect must be equidistant from the y-axis.

### Conclusion:
The correct statements under the given conditions are:
- The second parabola opens upward.
- The points of intersection are of equal distance from the y-axis.

Therefore, the answer to this question is:
- The second parabola opens upward.
- The points of intersection are of equal distance from the y-axis.