Question

A figure is reflected over the y-axis. Which of the following are true? The pre-image and image are congruent. The y-coordinates' signs change. The x-coordinates' signs change. The x-axis is the line of reflection.

Answer 1

When a reflection occurs, the original graph and the reflected graph are mirror images of each other. So, when the graph is reflected about the y-axis, think of the y-axis as the mirror. When you fold the graph length-wise, you will see that both graphs would coincide. Thus, their y-coordinate would not change. It would only change to the opposite quadrant, thereby changing the signs of the x-coordinates. So, as a rule, during reflection, the coordinates (x,y) is changed to (-x,y).

Therefore, the answer is:The x-coordinates' signs change..