Generally, whenever a point (x,y) is reflected across the y axis, the y coordinate stays the same and the sign of x coordinate changes.
So [tex](x,y)[/tex] changes to [tex](-x,y)[/tex].
Point D in the diagram shown has coordinates [tex](3,-1)[/tex]. According to the rule, the x-coordinate, 3, will change to -3 and the y-coordinate, -1, would stay the same.
Hence, our image of D after the reflection about y-axis would have coordinates [tex](-3,-1)[/tex].
ANSWER: [tex](-3,-1)[/tex]
