Slope-Intercept Form - Create Equation from Graph

Slope-Intercept - Create Equation from Graph - How it Works - Video

Example 1

Example 1:

One method to find the equation of the line is to use the slope-intercept formula, y = mx + b, where m is the slope and b is the y-intercept.

First we need to two points that cross both lines so we our points are integers. You can use any two points, but using integers is quicker. So we used the points (-3, -1) and (0, 1). 

Slope is rise/over. Rise is the how much the the graph changes vertically and run is how much the graph changes horizontally. Here the graph goes up 2 and goes to to the right 3. So the slope is 2/3.

B is the y-intercept of where the graph crosses the y-axis. With this graph, the line pass through the point (0, 1), so the y-intercept is 1.

Now that we have both the m and b, we can create the equation, y = 3x + 1.

Example 2

Example 2:

One method to find the equation of the line is to use the slope-intercept formula, y = mx + b, where m is the slope and b is the y-intercept.

First we need to two points that cross both lines so we our points are integers. You can use any two points, but using integers is quicker. So we used the points (-4, -2) and (0, -3). 

Slope is rise/over. Rise is the how much the the graph changes vertically and run is how much the graph changes horizontally. Here the graph goes down -1 and goes to to the right 4. So the slope is -1/4.

B is the y-intercept of where the graph crosses the y-axis. With this graph, the line pass through the point (0, -3), so the y-intercept is -3.

Now that we have both the m and b, we can create the equation, y = -1/4 * x - 3.

Example 3

Example 3:

One method to find the equation of the line is to use the slope-intercept formula, y = mx + b, where m is the slope and b is the y-intercept.

First we need to two points that cross both lines so we our points are integers. You can use any two points, but using integers is quicker. So we used the points (-3, -2) and (0, 2). 

Slope is rise/over. Rise is the how much the the graph changes vertically and run is how much the graph changes horizontally. Here the graph goes up 4 and goes to to the right 3. So the slope is 4/2.

B is the y-intercept of where the graph crosses the y-axis. With this graph, the line pass through the point (0, 2), so the y-intercept is 2.

Now that we have both the m and b, we can create the equation, y = 4/3*x + 2.

Example 4

Example 4:

Here we checked our work with the slope formula. 

We substituted the point (-3, -2) and (0, 2) in the slope formula, where (-3, -2) is (x1 , y1) and (0, 2) is (x2 , y2). So we get ...

So using the slope of the graph or the following formula will achieve the same result.

Live Worksheet 

Teacher - Edpuzzle Link