Stage: 5 Challenge Level: 
One solution is $x = 2$.
Can you discover whether this is the only solution and justify your claim?
Individual. Pythagoras' theorem. Mathematical reasoning & proof. Pentagons. Long problems. Calculating with ratio & proportion. chemistry. Other equations. Golden ratio. Quadratic equations.
Published October 1997.
Copyright © 2007. University of Cambridge. All rights reserved.
NRICH is part of the family of activities in the Millennium Mathematics Project, which also includes the Plus and Motivate sites.
email: nrich@damtp.cam.ac.uk