Improper Integral from 0 --> infinity [ ln x / ( 1 + x ^2) ]

peblez

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Int from 0 --> infinity [ ln x / ( 1 + x ^2) ]

I used integration by parts, but i get stuck doing the integral of arctan (x ) / x
 
\(\displaystyle \int_{0}^{\infty}\frac{ln(x)}{1+x^{2}}dx\)

That's because this particular one is not easily done by elementary means. This is a toughy to do using parts, substitution, etc.

If we look at the graph from 1 to infinity, it has the same area as from 0 to 1. 0 to 1 is below the x-axis and 1 to infinity is above the x-axis. They cancel one another out, leaving 0.

\(\displaystyle \int_{0}^{1}\frac{ln(x)}{x^{2}+1}dx\approx{-0.916}\)

\(\displaystyle \int_{1}^{\infty}\frac{ln(x)}{x^{2}+1}dx\approx{0.916}\)
 
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