The sum of the series frac{1}{{1 + {1^2} + {1 | vedclass

Name: Exam Paper Generator | JEE NEET Paper Generator | Vedclass
Brand: Vedclass
Rating: 5 (35 reviews)

Question

(B) Let $T_n$ be the $n^{th}$ term of the series.$T_n = \frac{n}{{1 + n^2 + n^4}} = \frac{n}{{(1 + n^2)^2 - n^2}}$$T_n = \frac{n}{{(n^2 + n + 1)(n^2 -

Vedclass · Accepted Answer

$\frac{{n(n + 1)}}{{2({n^2} + n + 1)}}$

Vedclass · Answer

(B) Let $T_n$ be the $n^{th}$ term of the series.$T_n = \frac{n}{{1 + n^2 + n^4}} = \frac{n}{{(1 + n^2)^2 - n^2}}$$T_n = \frac{n}{{(n^2 + n + 1)(n^2 - n + 1)}}$Using partial fractions:$T_n = \frac{1}{2} \left[ \frac{1}{n^2 - n + 1} - \frac{1}{n^2 + n + 1} \right]$$T_n = \frac{1}{2} \left[ \frac{1}{1 + (n - 1)n} - \frac{1}{1 + n(n + 1)} \right]$Now,the sum $S_n = \sum_{r=1}^n T_r = \frac{1}{2} \sum_{r=1}^n \left[ \frac{1}{1 + (r - 1)r} - \frac{1}{1 + r(r + 1)} \right]$This is a telescoping series:$S_n = \frac{1}{2} \left[ \left( \frac{1}{1} - \frac{1}{1 + 1(2)} \right) + \left( \frac{1}{1 + 1(2)} - \frac{1}{1 + 2(3)} \right) + \dots + \left( \frac{1}{1 + (n - 1)n} - \frac{1}{1 + n(n + 1)} \right) \right]$$S_n = \frac{1}{2} \left[ 1 - \frac{1}{1 + n(n + 1)} \right] = \frac{1}{2} \left[ \frac{1 + n^2 + n - 1}{n^2 + n + 1} \right] = \frac{n(n + 1)}{2(n^2 + n + 1)}$.

The sum of the series $\frac{1}{{1 + {1^2} + {1^4}}} + \frac{2}{{1 + {2^2} + {2^4}}} + \frac{3}{{1 + {3^2} + {3^4}}} + \dots$ to $n$ terms is

Similar Questions

The value of the expression $3(1!) - 4(2!) + 5(3!) - 6(4!) + \dots - 2008(2006)! + (2007)!$ is

The sum of the series $\frac{1}{\sqrt{1} + \sqrt{2}} + \frac{1}{\sqrt{2} + \sqrt{3}} + \frac{1}{\sqrt{3} + \sqrt{4}} + ... + \frac{1}{\sqrt{n^2 - 1} + \sqrt{n^2}}$ equals

$\frac{1}{3^{2}-1}+\frac{1}{5^{2}-1}+\frac{1}{7^{2}-1}+\ldots+\frac{1}{(201)^{2}-1}$ is equal to

$\prod\limits_{n = 1}^{10} {\left( {\frac{{6\sum\limits_{i = 0}^n i + 1}}{{6\sum\limits_{j = 0}^n {(j - 1)} + 1}}} \right)} $ is equal to

$\frac{1}{3 \times 7} + \frac{1}{7 \times 11} + \frac{1}{11 \times 15} + \ldots$ to $50$ terms $=$

Vedclass Test Series

Exam Paper Generator

Online Exam Module