In general, if and

then .

To graph them, you use a compass and straight-edge.

Draw an Argand Diagram and draw the line

Plot the point and join it to the origin. Now you have a right angle triangle. If you position your compass with its centre at the origin and tip at and draw the arc to the imaginary axis, you will have plotted .

Now draw a horizontal line from that point. If you join its intersection with to the origin, you will have a right angle triangle. By drawing the arc to the imaginary axis, you will now have plotted .

Draw a horizontal line from that point. Join its intersection with to the origin and you will have a right angle triangle. Draw the arc to the imaginary axis and you will have plotted .

Follow this process for as long as you like and you will have plotted the square roots of negative integers.