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Which point would map onto itself after a reflection across the line y = –x? (–4, –4) (–4, 0) (0, –4) (4, –4)

User Zein Makki
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2 Answers

1 vote

Answer:

D

Explanation:

Edge 2022

User Med Larbi Sentissi
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8.2k points
1 vote

Answer:

(4, -4)

Explanation:

A point that would map onto itself after a reflection across a line would need to be on the line in the first place.

For example, if you reflected point (2, 2) in the x-axis, the y-coordinate would become negative and so the reflected point would be (2, -2). If the point is not on the line, any reflection across a line will result in a change in at least one of the coordinates of the point.

Given line: y = -x

To find which point is on the given line, simply substitute the x-values of the given points and solve for y.

The answer options have three difference x-values: -4, 0, and 4

Substituting these into y = -x

x = -4 ⇒ y = -(-4) = 4 → (-4, 4)

x = 0 ⇒ y = -(0) = 0 → (0, 0)

x = 4 ⇒ y = -(4) = -4 → (4, -4)

Therefore, the only point that sits on the line is (4, -4) so this is the point that maps onto itself after a reflection in the line y = -x

For proof, see the attached diagram. Each original point is labelled A, B, C and D. When reflected in the line y = -x these points are A', B' C' and D'.

Which point would map onto itself after a reflection across the line y = –x? (–4, –4) (–4, 0) (0, –4) (4, –4)-example-1
User Alexpov
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8.3k points