Plotting coordinates

We can plot coordinates given by equations on a graph.

A graph is made of lines that connect the coordinates

Let’s take the equation $y = 2x + 1$

The equation describes a relationship between $x$ and $y$

If we change the value of $x$ then the value of $y$ changes

For example, if $x = 0$ then $y = 1$

This is because $y = 2x + 1$ which is $2 \times 0 + 1$ when $x = 0$

If $x = 1$ then $y = 3$

This is because $y = 2x + 1$ is now $2 \times 1 + 1$ when $x = 1$

We can make a table of the value of $y$ as we change the value of $x$ from 0 to 3

$y = 2x + 1$

The values in the table give us coordinate pairs that we can plot on graph paper like below.

The first coordinates are (0, 1)

Then we can plot (1, 3), (2, 5) and (3, 7)

We create the graph by joining up the coordinates with straight lines