Question

How do write the point-slope form of an equation for a horizontal line that passes through (5,-9)?

Answer 1

`y = 0x -9`, or just `y = -9`

Explanation:

The line is horizontal, therefore its slope is equal to 0.

All horizontal lines are written as `y = ....`

In `y = mx +c`, if the slope is 0, then there is no `x`-term and we have `y = c`

The y-value of the point that was given is the same as the y-intercept, because for any x-value, the y-value will always be the same. So `y = -9`

The equation of the line is

`y = 0x -9`