When you cannot simplify it further. The terms have no common factor besides 1 and A plus C does not have two numbers that multiply to the total and equal C.
Distance formula : d = sqrt (x2 - x1)^2 + (y2 - y1)^2
(-5,-9)...x1 = -5, and y1 = -9
(-5,13)...x2 = -5 and y2 = 13
now we sub and solve
d = sqrt (-5 - (-5)^2 + (13 - (-9)^2
d = sqrt (-5 + 5)^2 + (13 + 9)^2
d = sqrt (0^2 + 22^2)
d = sqrt (484)
d = 22 <==
