# Slope

**Slope as a Ratio**

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Slope is a measure of how steep a line is. It can be written as a ratio: how much the line is rising compared (divided by) to how much it’s moving forward. This can be expressed as rise over run. If a line is pointed up and to the right, it has a positive slope. If it is pointed up and to the left, it has a negative slope. A vertical line has an undefined slope and a horizontal line has no slope.

**Slope Formula**

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Since a line rising is change in its position on the y-axis, and how much it’s moving to the side is its change in its position on the x-axis, it can be expressed as change in y over (divided by) change in x. This is shown in the slope formula, which can be used to calculate the slope between two points without using a graph:

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Plug the x and y coordinates from you two points into the formula and solve for m. ‘m’ is the variable that typically represents slope in formulas.