{(2, 3), (1, 5), (2, 7)} - NOT because 2->3 and 2->7 {(11, 9), (11, 5), (9, 3)} - NOT because 11->9 and 11->5 {(3, 8), (0, 8), (3, -2)}
- NOT because 3->8 and 3->-2
When you reflect a point across the line y = x, the x-coordinate and y-coordinate change places. If you reflect over the line y = -x, the x-coordinate and y-coordinate change places and are negated (the signs are changed). the line y = x is the point (y, x). the line y = -x is the point (-y, -x).
