# Equations of other straight line graphs

The equation of a straight line on a graph is made up of a term, an term and a number, and can be written in the form of .

• The slope of the line is known as the gradient and is represented by the value of in the equation.
• The point at which the line crosses the -axis is the value of in the given equation, and is referred to as the -intercept.

### Examples

All the points that lie on the green line have a -coordinate that is the same as the -coordinate, eg:

and

We say that the equation of the line is .

All the points that lie on the purple line have a -coordinate that is one number higher than the -coordinate of the same line, eg:

and

In other words, the -coordinate equals the -coordinate .

So the equation of the line is .

Question

What is the equation of the line shown below?

The coordinates of the points are , and .

Here, the value is always twice the value.

The equation of the line that fits these and values is:

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