Writing Slope-Intercept Equations

Watch this lecture series and complete the interactive exercises to learn how to write an equation of a line in slope-intercept form.

Slope-intercept equation from graph - Question

Answers

1. y=-\frac{3}{2} x+3.

We are asked to complete the equation in slope-intercept form: y=m \cdot x+b. In this form, m gives us the slope of the line and b gives us its y-intercept.

By looking at the graph, we can see that the y-intercept is (0,3).

In order to find the slope, we need another point on the line whose coordinates are clearly visible. Such a point is (2,0).


Now, to find the slope, we need to take the ratio of the corresponding differences in the y-values and the x-values:

\frac{0-3}{2-0}=\frac{-3}{2}=-\frac{3}{2}

The equation is y=-\frac{3}{2} x+3.


2. y=2 x+4.

We are asked to complete the equation in slope-intercept form: y=m \cdot x+b. In this form, m gives us the slope of the line and b gives us its y-intercept.

By looking at the graph, we can see that the y-intercept is (0,4).

In order to find the slope, we need another point on the line whose coordinates are clearly visible. Such a point is  (1,6).

Now, to find the slope, we need to take the ratio of the corresponding differences in the y-values and the x-values:

\frac{6-4}{1-0}=\frac{2}{1}=2

The equation is y=2 x+4.


3. y=\frac{3}{4} x-2.

We are asked to complete the equation in slope-intercept form: y=m \cdot x+b. In this form, m gives us the slope of the line and b gives us its y-intercept.

By looking at the graph, we can see that the y-intercept is (4,1).


Now, to find the slope, we need to take the ratio of the corresponding differences in the y-values and the x-values:

\frac{1-(-2)}{4-0}=\frac{3}{4}

The equation is y=\frac{3}{4} x-2.


4. y=x-5.

We are asked to complete the equation in slope-intercept form: y=m \cdot x+b. In this form, m gives us the slope of the line and b gives us its y-intercept.

By looking at the graph, we can see that the y-intercept is (1,-4).

In order to find the slope, we need another point on the line whose coordinates are clearly visible. Such a point is  (1,-4).

Now, to find the slope, we need to take the ratio of the corresponding differences in the y-values and the x-values:

\frac{-4-(-5)}{1-0}=\frac{1}{1}=1

The equation is y=x-5.