AS/A2 Pure 2 Pure 3

P1 Topic 1: Proof
Fallacy 1
What is wrong with the proof below, which appears to show that if one number is bigger than another then it is in fact the same as that number!

There are six steps in total. Study each one in turn and see if you can spot the incorrect one. Move the mouse over the line itself and look at the status bar at the bottom to see a brief description of the step.

Summary You cannot divide by zero! Check the six steps again and you find that in step 6 both sides were divided by a-b-c. But a-b-c = 0 (see the first line). This page uses WebEQ. To speed up downloading you can install this WebEQ Math Viewer . Click on the Math Viewer icon and you will be taken to the download site.