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Question

Question: The coefficient of \(n^{- r}\)in the expansion of \(\log_{10}\left( \frac{n}{n - 1} \right)\)is....

The coefficient of nrn^{- r}in the expansion of log10(nn1)\log_{10}\left( \frac{n}{n - 1} \right)is.

A

1rloge10\frac{1}{r\log_{e}10}

B

1rloge10- \frac{1}{r\log_{e}10}

C

1r!loge10- \frac{1}{r!\log_{e}10}

D

None of these

Answer

1rloge10\frac{1}{r\log_{e}10}

Explanation

Solution

We have S=S_{\infty} =

=loge(n1n)log10e= - \log _ { e } \left( \frac { n - 1 } { n } \right) \cdot \log _ { 10 } e e3e2\frac{e^{3} - e}{2}

Therefore coefficient of e32\frac{e - 3}{2}is 1+x22!+x44!+......1 + \frac{x^{2}}{2!} + \frac{x^{4}}{4!} + .......