Linear Graph

Key Stage 4

When a relationship between two variables is linear they increase by a constant amount in relation to one another.

A scatter graph showing a linear relationship has straight line of best fit.

On a linear graph; when one variable increases, the other increase or when one increases the other decreases.

A linear relationship may have a non-zero y-intercept.

If the line of best fit on for a linear relationship has a y-intercept of zero then it is called 'directly proportional'.


This scatter graph shows a linear relationship where x increases and y increases. \(y = mx + c\) Where m, the gradient, is positive.	This scatter graph shows a linear relationship where x increases and y decreases. \(y = mx + c\) Where m, the gradient, is negative.	This scatter graph shows a linear relationship that is directly proportional where x doubles, y doubles. \(y = mx\) Where m, the gradient, is positive.