my teacher asked me this question and said you have to go through logical way to solve this problem..i could not do thia plz help me:::

∫ lower limit 1,upper limit ∞:ln(x)/x dx

any help is appreciated:

actually in this problem take ln(x) =u as the substitution at last you get  U.du    as the integrand which on integrating gives you u^2/2. u= lnx on substituing it and applying the limits you get your answer. There is no such a big logic in this sum. Hope this helps you and if you really want to do a good problem Do this:-

∫ (x^2+1)/x^4+kx^2+1. Hope the answer given by me helps U. Cheers man.