Answer:
The rule for finding a reflection of a point across the y-axis is that the y-coordinate will stay the same but the x-coordinate will become its opposite. Thus, in the context of the problem, point (3,6) would become (-3,6) if reflected across the y-axis.
Step-by-step explanation: If you were going to reflect a point across the x-axis, the x-coordinate would stay the same. You're not moving it and it shouldn't change signs. The y-coordinate, however, would become its opposite because it'd be joining a new quadrant. Think of it like this:
Y-AXIS = Y remains the same and gains a neighbor; X changes because it isn't the center of attention.
X-AXIS = X remains the same and gains a neighbor; Y changes because it isn't the center of attention.
Basically, the letter of the axis is the number that doesn't change.
I hope I helped!
