Sunday, 13 January 2019

real analysis - To find the sum of the series ,1+frac13cdot4+frac15cdot42+frac17cdot43+ldots




The answer given is log3.
Now looking at the series



1+134+1542+1743+=i=01(2n1)4nlog3=i=1(1)n+12nn




How do I relate these two series?


Answer



Hint: a common series that is used for computing log of any real number is
log(1+x1x)=2(x+x33+x55+x77+)
u=1+x1xx=u1u+1


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