Final answer:
The image point of (4, -9) after the transformation R90° about the y-axis is (-9, -4).
Step-by-step explanation:
To find the image point of (4, -9) after the transformation R90° about the y-axis, we need to rotate the point 90 degrees counterclockwise around the y-axis. When rotating a point in 2D about the y-axis, the x-coordinate remains the same, but the y-coordinate becomes its negative. Therefore, the image point is (-9, -4).