Persamaan titik melalui p 3,5 dan q 2,-2

y-y1 / y2-y1 = x-x1 / x2-x1
y-5 / -2-5 = x-3 / 2-3
-1(y-5) = -7(x-3)
-y+5 = -7x+21
-y = -7x+21-5
-y = -7x+16
y = 7x-16