To draw the line y = x: Plot points with coordinates where x and y are equal. Three points are sufficient, but more can be plotted. Draw a line through the plotted points.

When you graph a series of (x,y) coordinates in Microsoft Excel 2010, you can use the program's built-in functions to display the equation for the line created by those data points.

Revise how to plot a linear equation graph. Learn how to read x and y coordinates from a graph in this BBC Bitesize maths KS3 guide.