1. Millburn Academy
Maths department
Higher
Equation of a
Straight Line

2. Find the gradient of the line joining the points (a,b) and (x,y).
(a,b)
This gives us the equation of a straight line with gradient m and passing through the point (a,b).
Swap sides.
Multiply both sides by ( x – a).
Substitute coordinates.
Write the gradient formula.

3. Example 1
Find the equation of the line with gradient 3 and passing through the point (4,-1)

4. Example 2
Find the equation of the line with gradient ¾ and passing through the point (-2,5)

5. Example 3
Find the equation of the line through the points (-2,1) and (2,9).