tentukan persamaan garis lurus melalui dua titik  A (2,3) dan B (4,5)

y - y1 = x - x1
y2 -y1= x2-x1 

jadi y = x + 1

y-y1 / y2-y1 = X-X1 / X2-X1
Y-3 / 5-3 = X-2 /4-2
Y-3 / 2 = X-2 / 2
2X-4 = 2Y-6
2X-2Y = -6 + 4
2x-2y = -2
2x-2y+2 = 0