I don't know......
But good question......
(Why?) ...write...
http://www.mathhelpforum.com/math-help/number-theory/65693-divisibility-14-a.html
I think...Maybe use binomial theorem...
If your'e trying to prove that a^k|b^k => a|b then
a^k=nb^k
(a/b)^k=n
a/b=n^1/k
Now a|b iff n=m^k for some integer m, the problem is to show that it is so.
You can assume by contradiction that a!|b which means there exists p and r such that:
a=pb+r r<=b
Now write a^k=(pb+r)^k and see that it contradicts our assumption.