Question

d. describe the transformation (x,y)→(x, -y) in words.

Explanation:

The transformation changes the sign of the y - coordinate of each point (x, y) while keeping the x - coordinate the same. This is a reflection over the x - axis.

Answer:

The transformation (x, y) → (x, -y) is a reflection of the point (x, y) over the x - axis.