Reflection rule over y - axis is given as
(x , y) ------------ (-x, y)
This implies that the y - axis will remain the same and the x - axis will be negated
Pre image ABC at point (2, -1)
The reflection over y - axis will be
ABC A'B'C' A''B''C'' A'''B'''C'''
(2, -1) -----------------(-2, -1) ----------------------(2, -1) -------------------(-2, -1)
ABC A'B'C' A''B''C'' A'''B'''C'''
(2, -4) (-2, -4) (2, -4) (-2, -4)