On Tuesday, April 23, 2013 3:28:44 PM UTC+1, oercim wrote: > Sorry, you are right, so let modify: > > > > x1^2+x2^2+....+xn^2>=ave(x)^2 > > > > does this inequality always hold? Thanks a lot.
Ok, I solved it. Just giving the answer won't help much. Try looking at related problems that are simpler. For example, what happens if n is small such as 1, 2 or 3? What happens if you replace squaring by an even simpler function?