Question

Which matrix represents the image of the triangle with vertices at (-2, 0), (1, 5), and (4, -8) when reflected over the line, y = -x?

Answer 1

One way you can figure this out is to draw the line y=-x and the vertices of the triangle. Then make a 2x2 matrix with variables in them, so that when you multiply by these vectors what you get is the reflected point, and you can solve for the matrix. Try it out, and I'll help you out.