Question

How do you tell when the slope is negative?

Answer 1

Look at the Rise/run: if rise / run is positive, then it the slope is positive. If the rise / run is negative, then the slope is negative. (In order to be positive, both numbers must have the same symbol ; ex +4/+7 or -2/-5. For it to be negative both values to be different symbols ex -4 / +1 or 6/-11)

Answer 2

If the line goes downhill as you read from left to right, then the slope is negative.

The slope is positive when you go uphill, reading from left to right.

A slope of 0 means the line is completely horizontal or level

If the line is completely vertical, then the slope is undefined.