persamaan garis yg melalui titik A(3,4) dan titik B(5,8) adalah....

(y - y1) / (y2 - y1) = (x - x1) / (x2 - x1)
(y - 4) / (8 - 4) = (x - 3) / (5 - 3)
(y - 4) / 4 = (x - 3) / 2
2(y - 4) = 4(x - 3)
2y - 8 = 4x - 12
2y - 4x = - 12 + 8
2y - 4x = - 4

pers garis
2y - 4x = - 4