what is the equation of the following line written in general form?
y - x + 1 = 0
x - y + 1 = 0
-x - y + 1 = 0
feel free to explain how i do this b/c i have a few assignments like this

I'm pretty sure it would be x - y + 1 = 0 because if you plug in one of the coordinates into each equation, this is the only one that works.

y - x + 1 = 0
2 - 1 + 1 = 0
2 = 0 not correct

x - y + 1 = 0
1 - 2 + 1 = 0
0 = 0 correct

-x - y + 1 = 0
-1 - 2 + 1 = 0
-2 = 0 not correct