# How do I use the graph of a linear function to find its equation?

##### 1 Answer

If you have two points on the graph, you can calculate the equation.

Select any two point on the graph. It may make life easier to have two points that are on gridlines in your graph. If one of the points is the

(the

You want to find the equation

where

**To calculate the slope #m#**

Let's call the two points you selected

Then the slope is how fast

Or in formula (in formulae,

**To calculate the intercept #b#**

If one of the points you selected is on the

Otherwise you fill in the equation

(substituting the

**One example**

*Step 1:* finding

Your points are

*Step 2* : finding

Substitute

The complete equation will be:

*Step 3:* check! your answer:

Fill in the