Question

What is the slope of `y=-1`?

Answer 1

`0`

Explanation:

The slope `m` of a line passing through points `(x_1, y_1)` and `(x_2, y_2)` is the change in `y` divided by the change in `x`:

`m = (Delta y)/(Delta x) = (y_2-y_1)/(x_2-x_1)`

In our example, the line `y = -1` passes through `(0, -1)` and `(1, -1)`, giving us a slope:

`m = (-1 - (-1))/(1 - 0) = 0/1 = 0`

The `y` value does not change, while the `x` value does.