Answer:
3x -4y = 2
Explanation:
A plot of the points makes it clear that the longest diagonal is BD. The 2-point form of the line through those points can be found by filling in ...
y = (y2 -y1)/(x2 -x1)(x -x1) +y1
y = (4 -(-2))/(6 -(-2))(x -(-2)) +(-2) . . . . . fill in points B and D
y = (6/8)(x +2) -2
4y = 3(x +2) -8 . . . . . . multiply by 4
3x -4y = 2 . . . . . . . . . . add 2-4y