persamaan garis yang melalui titik (-3,-1) dan (2,4) adalah

(y-y1)/(y2-y1) = (x-x1)/(x2-x1)
(y-(-1))/(4-(-1)) = (x-(-3))/(2-(-3))
(y+1)/5=(x+3)/5   ...(lima di coret)
y+1 = x+3
y = x+2

Bab Persamaan Garis
Matematika SMP Kelas VIII

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

** coret 5 **

y + 1 = x + 3
y = x + 3 - 1
y = x + 2