How to find the general form (Ax-By-C = 0) of a line with an undefined slope This is how the question reads:
"The equation of the line that goes through the points (3, -6) and (3, 10) can be written in general form Ax + By + C = 0 where A = _ B = _ and C = ____" I know the answer for B is 0 but am unable to find the solutions for A and B. Please help!

This is a vertical line since it passes through two points with the same horizontal coordinate ($3$). Vertical lines always have an equation of the form $x=k$. In this case, $k=3$ by inspection. In your general form this is
$$1x-0y-3=0,$$
right?
Addendum: It would be very much worth your time to memorize the fact that vertical (horizontal, resp.) lines have equations of the form $x=k$ ($y=k$, resp.), and that they are characterized by the fact that all points on them have the same horizontal (vertical, resp.) coordinate.
