Calculating Limit of an Integral

  • Thread starter Thread starter BobSun
  • Start date Start date
  • Tags Tags
    Integral Limit
BobSun
Messages
4
Reaction score
0
Limit of an integral
1. Homework Statement
Evaluate:
the limit as n goes to \infty of
\int^{1}_{0} (n^{3/2}x^{5/4})/(1+n^{2}x^{2})dx
dx is the lebesgue measure

2. Homework Equations
I thought I could use the monotone convergence theorem or the dominated convergence theorem neither work.

3. The Attempt at a Solution
the intregrand is dominated by 1/\sqrt{x} but 1/\sqrt{x} isn't lebesgue integrable.
 
Physics news on Phys.org
?? 1/\sqrt{x}= x^{-1/2} surely is Lebesque integrable on [0,1]. In fact, it is Riemann integrable and its integral from 0 to 1 is just \left 2x^{1/2}\right|_{x=0}^1= 2.
 
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