How do you find the slope of a line?

Answer 1

The slope of a line is found by dividing a change in the y value by the change in the x value through the same length of the line being investigated. It can said to be the delta y over the delta x, or the change in y over the change in x (for a given segment of the line). We can also say "rise over run" of the line and mean the same thing. The slope of a line is a pure number, one without units. And it can have a positive or negative sign. A line that goes "up" when it goes from left to right has a positive slope. A line that goes "down" when going from left to right will have a negative slope. Picture a graph with a unit on the x axis equal in length to a unit on the y axis. A line of exactly 45 degrees to the horizontal (or vertical, for that matter) will have a slope of exactly 1 if it slopes up from left to right. The same line sloping down from left right will have a slope of -1. Lines of less than 45 degrees to the horizontal will have slopes of less than 1. Lines with angles greater than 45 degrees to the horizontal will have slopes of greater than 1. The signs of all these lines will be in accordance with the above suggestions, i.e., lines going up from left to right have positive slope, and going down from left to right have negative slopes.

Answer 2

Points: (x1, y1) and (x2, y2)

Slope: y1-y2/x1-x2