Answered

Which point would map onto itself after a reflection across the line [tex]\( y = -x \)[/tex]?

A. [tex]\((-4, -4)\)[/tex]

B. [tex]\((-4, 0)\)[/tex]

C. [tex]\((0, -4)\)[/tex]

D. [tex]\((4, -4)\)[/tex]



Answer :

To determine which point maps onto itself after a reflection across the line [tex]\(y = -x\)[/tex], we need to apply the reflection transformation to each point.

When a point [tex]\((x, y)\)[/tex] is reflected across the line [tex]\(y = -x\)[/tex], its image is [tex]\((-y, -x)\)[/tex].

Let’s examine each given point:

1. Point [tex]\((-4, -4)\)[/tex]:
- Reflecting [tex]\((-4, -4)\)[/tex] across the line [tex]\(y = -x\)[/tex], we get:
[tex]\[ (-(-4), -(-4)) = (4, 4) \][/tex]
- The reflected point is [tex]\((4, 4)\)[/tex], which is not equal to the original point [tex]\((-4, -4)\)[/tex].

2. Point [tex]\((-4, 0)\)[/tex]:
- Reflecting [tex]\((-4, 0)\)[/tex] across the line [tex]\(y = -x\)[/tex], we get:
[tex]\[ (-0, -(-4)) = (0, 4) \][/tex]
- The reflected point is [tex]\((0, 4)\)[/tex], which is not equal to the original point [tex]\((-4, 0)\)[/tex].

3. Point [tex]\((0, -4)\)[/tex]:
- Reflecting [tex]\((0, -4)\)[/tex] across the line [tex]\(y = -x\)[/tex], we get:
[tex]\[ (-(-4), -0) = (4, 0) \][/tex]
- The reflected point is [tex]\((4, 0)\)[/tex], which is not equal to the original point [tex]\((0, -4)\)[/tex].

4. Point [tex]\((4, -4)\)[/tex]:
- Reflecting [tex]\((4, -4)\)[/tex] across the line [tex]\(y = -x\)[/tex], we get:
[tex]\[ (-(-4), -4) = (4, -4) \][/tex]
- The reflected point is [tex]\((4, -4)\)[/tex], which is equal to the original point [tex]\((4, -4)\)[/tex].

Thus, the point that maps onto itself after a reflection across the line [tex]\(y = -x\)[/tex] is [tex]\((4, -4)\)[/tex].