Suppose we sketch the graphWe obtain the graph below.

We can use the graph to solve the equationby finding the intersection of the graph with the– axis, since this is whereSuppose we want to solve a different equation – for example,We could sketch the graph ofand find the intersection of the graph with the– axis. It is quicker however to subtract the equation from the expression of the graph above.

minus

equals

Plotting the graph ofon the diagram above gives the diagram

The solution tois where the– values of the points where the graphs cross. These areand