Year 8 Interactive Maths - Second Edition

Plotting Linear Graphs

To plot a straight line graph we need to find the coordinates of at least two points that fit the rule.

Example 6

Plot the graph of y = 3x + 2.

Solution:

Construct a table and choose simple x values.

The table of values obtained after entering the values of y is as follows:

Draw a Cartesian plane and plot the points.  Then join the points with a ruler to obtain a straight line graph.

Setting out:

Often, we set out the solution as follows.

Example 7

Plot the graph of y = –2x + 4.

Solution:

Key Terms

linear graph, plotting a linear graph, straight line graph