tentukan persamaan garis yg melalui titik (2,1)dan (3,5)

(y - y1) / (y2 - y1) = (x - x1) / (x2 - x1)
(y - 1) / (5 - 1) = (x - 2) / (3 - 2)
(y - 1) / 4 = (x - 2) / 1
1 (y - 1) = 4 (x - 2)
y - 1 = 4x - 8
y - 4x = - 8 + 1
y - 4x = - 7

pers garis
y - 4x = - 7