persamaan garis lurus melalui titik (4,-1) dan (2,5)

y-y1 / y2-y1 = x-x1 / x2-x1
y+1 / 5+1 = x-4 / 2-4
y+1 / 6 = x-4 / -2

-2(y+1) = 6(x-4)
-2y-2 = 6x-24
-2y = 6x-24+2
-2y = 6x-22
------------------- : -2
y = -3x+11
3x+y = 11
3x+y-11 = 0

Semoga membantu
Maaf kalau salah