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“What is the slope of a vertical line?” is a typical question when you start to analyze graphs and linear equations. To answer that, let’s go ago to the an easy definition.

You are watching: Vertical lines always have a slope of zero

Slope is defined as the steepness, incline, or gradient of a line. That is likewise defined as the change in y value ("rise") over the readjust in x worth ("run"). The slope formula is:

Finding Slope

Normally in a straight equation, the slope of the line is most easily calculated by putting the equation the the heat in slope-intercept form, or y=mx+b style (as opposed to conventional form).

Here, the change m represents the slope. You deserve to have a optimistic slope or negative slope relying on its value.

The formula for a horizontal heat (y = -1, because that example), matches the slope-intercept form, simply without an mx. That means it has no slope!

However, the formulas for vertical lines (x = 4, because that example), can not be put right into slope-intercept form. We"ll show you why this is a little later.

What Is the steep of a Horizontal Line?

The slope of a horizontal line is 0 since the line does not increase at all. In other words, for any two point out on the straight line, the change in y-value will constantly be 0.


What Is the steep of a upright Line?

The steep of a vertical line is undefined. That’s because, in a horizontal line, the adjust in the x-value will constantly be 0. You can figure this out by calculating the horizontal difference in between the 2 x-coordinates. Psychic the steep formula:

With a vertical line, this outcomes in a bottom denominator the 0. However, dividing by 0 is something the doesn’t exist in math! also though the difference in y-coordinate may change, dividing any number through the change in x-coordinate, 0, will result in an undefined slope.

See more: The Multiplicative Inverse Of A Negative Fraction, Multiplicative Inverse & Reciprocal


Remember the steep Formula

When graphing direct equations, remember the m, the slope, is calculation by detect the vertical readjust between 2 points separated by the horizontal readjust between those two points.

However, remember these two distinct cases: Horizontal lines have a slope of 0 due to the fact that the vertical change is 0. Vertical lines have actually an undefined slope due to the fact that the horizontal readjust is 0 — friend cannot divide a number through 0.