Copyright © University of Cambridge. All rights reserved.

'Weekly Problem 39 - 2009' printed from http://nrich.maths.org/

Show menu


Show that $(1+x+y)^2-(1-x-y)^2$ is divisible by $4$ for all values of $x$ and $y$.

If you liked this problem, here is an NRICH task which challenges you to use similar mathematical ideas.

 

 

This problem is taken from the UKMT Mathematical Challenges.

View the previous week's solution
View the current weekly problem