Question

what is the equation of a line, in general form, with a point (-3, 0) and an undefined slope

Answer 1

An undefined slope refers to a vertical line on the graph. (A zero line refers to a horizontal line on the graph)

So if the undefined slope, which is  a vertical line, passes through (-3, 0).

The equation of the line is x = -3.   Because on the graph x = a number is a vertical line.

So equation of line is   x = -3