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Root mean square help 
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#1
Nov2909, 08:34 AM

P: 91

Hello,
For 1 and 2 I want to calculate rms then [tex]x_{rms}=\sqrt{\frac{1}{n}\sum_{i=1}^{n}x_i^2}\Rightarrow x_{1,2}=\sqrt{\frac{1}{2}(1^2+2^2)}=\sqrt{\frac{5}{2}}[/tex] And also [tex]x_{rms}=\sqrt{\frac{1}{x_2x_1}\int_{x_1}^{x_2}f^2(x)dx}[/tex] For the function [tex]f(x)=x[/tex], [tex]x_1=1[/tex], [tex]x_2=2[/tex] [tex]x_{rms}=\sqrt{\frac{1}{21}\int_{1}^{2}x^2dx}=\sqrt{\frac{7}{3}}[/tex] Please explain to me where I do wrong. Thanks 


#2
Nov2909, 01:39 PM

P: 240

You do nothing wrong
Are you expecting to get the same value? Well you won't because the discrete set {1,2} is different from the continuous set {x  1<x<2}, therefore you shouldn't get the same value 


#3
Nov3009, 05:33 AM

P: 91




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