Originally Posted by

**shaoen01** Hi all,

I am having problem of trying to apply the well ordering principle. I know what it is, but i find it difficult to apply it. If anyone knows of any good website that has a lot of useful information, please do let me know. I do not know where to start working on a solution, and i am terribly lost. Below are my questions:

Qns 1:

Use the well-ordering principle to prove that if a and b are positive integers, then there exist integers u,v such that gcd(a,b) = ua+vb.