Carl is making a rectangular dog run. he has 36 one-yard sections of fence that he plans to use to keep his dig inside. he wants the run to be as long as possible. what is the longest whole-number length can he use for the run?

From the given condition, it must be seen to it that the width must also be the lowest whole-number possible. Thus, the width should be equal to 1 yard. The given 36 is the perimeter of the run.
                                 P = 2L + 2W
                                36 = 2L + 2(1)
                                      L = 17
Thus, the longest whole-number length is equal to 17 yards. 

The correct graph is the second one, with the points being at (-6,0), (2,0) and reaching down to (-2,-8)