Uniform Convergence of sequence

siddharth
Homework Helper
Gold Member
Messages
1,142
Reaction score
0
Discuss the uniform convergence of the following sequence in the interval indicated

{x^n} , 0< x <1

Now,
f(x) = \lim_{n\rightarrow \infty} f_{n}(x) = 0
Therefore given any small \epsilon > 0, if there exists N such that |f_n(x)-f(x)| < \epsilon for all n \geq N for all x in the given interval, then f_n(x) is uniformly convergent.

That gives

x^n < \epsilon

n > \frac{\log \epsilon }{\log x}

So, it is not possible to fix an N such that the above condition is satisfied for all values of n>N because for a given value of N, I can always find a value of x close to 1 such that the above condition is not valid.
Hence x^n is not uniformly convergent in the given interval.

Is my above reasoning correct?
 
Last edited:
Physics news on Phys.org
xn is convergent, just not uniformly convergent. Does that make sense?
 
Last edited by a moderator:
There are two things I don't understand about this problem. First, when finding the nth root of a number, there should in theory be n solutions. However, the formula produces n+1 roots. Here is how. The first root is simply ##\left(r\right)^{\left(\frac{1}{n}\right)}##. Then you multiply this first root by n additional expressions given by the formula, as you go through k=0,1,...n-1. So you end up with n+1 roots, which cannot be correct. Let me illustrate what I mean. For this...
Back
Top