persamaan garis 1,-3 dan -3,1

(1,-3)(-3,1)
x1 = 1
x2 = -3
y1 = -3
y2 = 1

y-y1/y2-y1 = x-x1/x2-x1
y-(-3)/1-(-3) = x-1/-3-1
y+3/1+4 = x-1/-4
y+3/5 = x-1/-4
-4(y+3) =5(x-1)
-4y-12 = 5x-5
-4y = 5x-5+12
-4y = 5x+7

5x+4y+7 = 0