Question

The point (–5, –9) was reflected over an axis to become the point (5, –9). Which axis was it reflected over? Explain.
x-axis, because the x-coordinate is the opposite
x-axis, because the y-coordinate is the opposite
y-axis, because the x-coordinate is the opposite
y-axis, because the y-coordinate is the opposite

Answer 1

y-axis, because the x-coordinate is the opposite.

Reflection across the y-axis maps (x, y) to (−x, y). Here (−5, −9) becomes (5, −9), so only the x-coordinate changed sign.