This video explains how to find the equation of a line when given 2 points.

Find the slope using the slope formula, .

After finding the slope, plug in the value of your points into either slope-intercept form, or point-slope form, to get the equation of the line.

## Video-Lesson Transcript

Let’s find an equation of a line, given two points.

How do we do this?

We can solve this by using the slope intercept form:

or by using point-slope formula:

But in both cases we need to know what the slope (m) is.

So the first step is to find the slope.

The formula for finding the slope is

For example:

Find the equation of a line with given points and

First, let’s find the slope.

Let’s label the given:

So now, we can find the equation of a line using the slope intercept form or the point slope form.

Let’s do the slope intercept form first.

Now, you can substitute any of the paired coordinates but not both.

I’m going to use the second pair of coordinates ,

Now, let’s solve for

Now, we know what the y-intercept is and the slope.

So the equation becomes

Now, let’s solve using the point-slope form.

Here, we can choose which pair to use as coordinates.

So let me choose the first set of coordinates ,

Also, we already know what the slope is

Now, let’s solve

Let’s get by itself by adding on both sides.

And our answer is

which is the same as the first one.

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