Sequence And Series Question 561

Question: $ {\log_{e}}(1+x)=\sum\limits_{i=1}^{\infty }{

[ \frac{{{(-1)}^{i+1}}x^{i}}{i} ]} $ is defined for [Roorkee 1990]

Options:

A) $ x\in (-1,,1) $

B) Any positive (+) real x

C) $ x\in (-1,,1] $

D) Any positive (+) real $ x(x\ne 1) $

Show Answer

Answer:

Correct Answer: C

Solution:

$ {\log_{e}}(1+x)=\sum\limits_{i=1}^{\infty }{\frac{{{(-1)}^{i+1}}x^{i}}{i}} $ is defined for $ x\in (-1,1] $ Because $ {\log_{e}}(1+x)=x-\frac{x^{2}}{2}+\frac{x^{3}}{3}-\frac{x^{4}}{4}+….\infty $ is defined for $ (-1<x\le 1) $ .



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