Question

How do you find the slope for `x = -2`?

Answer 1

The slope of a vertical line (i.e. `x = a`) is undefined (or you could say it is `oo`).

In opposition, the slope of an horizontal line (i.e. `y = a`) is `0` since the standard form of a linear function is `y=mx+a`, where `m` is the slope.