The domain and range are defined for a relation and they are the sets of all the x-coordinates and all the y-coordinates of ordered pairs respectively. For example, if the relation is, R = {(1, 2), (2, 2), (3, 3), (4, 3)}, then: Domain = the set of all x-coordinates = {1, 2, 3, 4} Range = the set of all y-coordinates = {2, 3} take a look at the picture e.g Here, the domain is the set {A,B,C,E} { A , B , C , E } . D D is not in the domain, since the function is not defined for D D .
The range is the set {1,3,4} { 1 , 3 , 4 } . 2 2 is not in the range, since there is no letter in the domain that gets mapped to 2 2 .
B simply does not work because in order for 4 to be subtracted by another number to equal 18, that number (width) would have to be negative
C also isn't correct since if it was solved out, we would add four to both sides, making the left side equal to w/2 + 4 which isn't what we want because the length is 4 shorter, not longer
D can be dealt with in the same way, by adding w/2 on both sides, making the left side 4 + w/2, the same as the previous option.
