Bantu yaa,cari Fungsi garis K,dengan caranya,makasih

Garis k melalui (2, 1) dan (0, -1)
(y2 - y1)/(x2 - x1) = (y - y1)/(x - x1)
(-1 - 1)/(0 - 2) = (y - 1)/(x - 2)
-2/-2 = (y - 1)/(x - 2)
1 = (y - 1)/(x - 2)
y - 1 = x - 2
y = x - 2 + 1
y = x - 1