Tentukan persamaan garis yang melalui titik(1,2)dan (-2,5)!

pakai rumus Y-Y1/Y2-Y1 = X-X1/X2-X1

misal x1, y1 = (1,2)
x2,y2 = (-2,5)

jadinya
Y-2/5-2 = X-1/-2-1
Y-2/3 = X-1/-3
-3(Y-2) = 3(X-1)
-3Y+6 = 3X-3
-3Y+9 = 3X

Y-3=X ⇒ pers. garis

y-y1/y2-y1=x-x1/x2-x1
y-2/5-2=x-1/-2-1
y-2/3=x-1/-3
3x-3=-3y+6
3x+3y=6+3
3x+3y=9
x+y=3