I think this should help :-)
1. The points that are in given in the (x, y) form aka (x-coordinate, y-coordinate).
2. The range is the set of values onto which ƒ sends the x's.
The x's are sent the numbers 1, 2, 3, 1, 7 which ends up looking like {1,2, 3, 7}
So the answer is {1,2,3,7}