Point-Slope form of the line

The point-slope form of the line with slope m containing the point (x0; y0) is the equation:
 y - y0 = m(x - x0)

Example

Write the equation of the line containing the points (-1; 3) and (2; 1).


Solution

 In order to use the Equation above we need to find the slope of the line in question so we
use the slope of a line equation to get m.

m= (y1 - y0) / (x1 - x0) = (1-3) / [2-(-1)]= - 2 / 3

 Now we use the point (-1 , 3) as (x0, y0) and we get:

If we use the point (2, 1) as (x0, y0) in point slope equation, we wil get the same result.