|Check||a = b||Given|
|Check||ab = b^2||Multiply both sides by b|
|Check||ab - a^2 = b^2 - a^2||Subtract a^2 from both sides|
|Check||a(b-a) = (b + a)(b - a)||Factor both sides|
|Check||a = b + a||Divide by (b - a)|
|Check||a = a + a||Given a = b|
|Check||a = 2 * a||Simple addition|
|Check||1 = 2||Divide by a|
There is only one illegal step in this proof. Click on the button next to the step you think is invalid. The correctness of your choice will be displayed after a brief waiting period. The correct answer has the shortest waiting period.
Created by Andrew Freed, firstname.lastname@example.org on April 7, 2002.
Modified by Andrew Freed, email@example.com on April 15, 2002.
Development of this resource was sponsored by the Penn State Fund for Excellence in Learning and Teaching (FELT), project "Java-based Teaching of Mathematics in Information Sciences and Technology", supervised by Frank Ritter and David Mudgett.