Sequence And Series Question 55

Question: $ \frac{4}{1,.,3}-\frac{6}{2.4}+\frac{12}{5,.,7}-\frac{14}{6,.,8}+…..\infty = $

Options:

A) $ {\log_{e}}3 $

B) $ {\log_{e}}2 $

C) $ 2,{\log_{e}}2 $

D) None of these

Show Answer

Answer:

Correct Answer: B

Solution:

$ S=\frac{4}{1.3}-\frac{6}{2.4}+\frac{12}{5.7}-\frac{14}{6.8} $ +…. $ =\frac{1+3}{1.3}-\frac{2+4}{2.4}+\frac{5+7}{5.7}-\frac{6+8}{6.8}+…. $ $ =( \frac{1}{1}+\frac{1}{3} )-( \frac{1}{2}+\frac{1}{4} )-( \frac{1}{5}+\frac{1}{7} )-( \frac{1}{6}+\frac{1}{8} )+…. $ $ =1-\frac{1}{2}+\frac{1}{3}-\frac{1}{4}+\frac{1}{5}-\frac{1}{6}+….={\log_{e}}2 $ .