Sequence And Series Question 463

Question: $ 1+\frac{4^{2}}{3,!}+\frac{4^{4}}{5,!}+……\infty = $

Options:

A) $ \frac{e^{4}+{e^{-4}}}{4} $

B) $ \frac{e^{4}-{e^{-4}}}{4} $

C) $ \frac{e^{4}+{e^{-4}}}{8} $

D) $ \frac{e^{4}-{e^{-4}}}{8} $

Show Answer

Answer:

Correct Answer: D

Solution:

$ S=1+\frac{4^{2}}{3\ !}+\frac{4^{4}}{5\ !}+……..\infty $ $ =\frac{1}{4}{ 4+\frac{4^{3}}{3\ !}+\frac{4^{5}}{5,!}+…… }=\frac{1}{4}( \frac{e^{4}-{e^{-4}}}{2} ) $ .