The vertices of an triangle are P(2, -4) Q(-5, 3) R(-1,-2). What are the vertices of the image reflected across the y-axis

When a point is reflected across the y-axis, the x-coordinate changes sign while the y-coordinate remains the same. Thus, to find the image of the triangle across the y-axis, we must negate the x-coordinates of each vertex:

P' = (-2, -4)
Q' = (5, 3)
R' = (1, -2)

Therefore, the vertices of the image of the triangle across the y-axis are P'(-2, -4), Q'(5, 3), and R'(1, -2).