1. Finding the equation of a line
Given two points

2. Consider the line joining (-2, 5) and (6, -1)
Example:
Consider the line joining (-2, 5) and (6, -1)
The slope joining any two points on the line must be the same x y
(-2, 5)
y = rise
•(x, y)
(6, -1)
x = run
So the slope joining (x, y) to any other point on the line must be the same.
Any point on the line (x, y) must satisfy the conditions of this equation

3. We can simplify the following equation by cross multiplying
Expand the brackets
Isolate y
Simplifying, we get the equation of the line
slope
y-int

4. In practice we will calculate the equation as follows:
A line passes through the points (-2, 5) and (6, -1)
Find the slope of the line:
b) Find the equation of the line:
Replace m, x and y
Use the point (-2, 5)