Question
योगफल $\sum_{r=1}^{10}\left(r^{2}+1\right) \times(r !)$ बराबर है 

Answer

b
$\sum\limits_{R - 1}^{10} {({r^2} + 1)r!} $

${T_1} = ({r^2} + 1 + r - r)r! = ({r^2} + r)r! - (r - r)r!$

${T_1} = rr! + r - (r - 1)r!$

${T_1} = 1\,2! - 0$

${T_2} = 2\,3! - 1\,2!$

${T_3} = 3\,4! - 2\,3!$

${T_{10}} = 10\,11! - 9\,10!$

$\sum\limits_{R - 1}^{10} {({r^2} + 1)} \,r! = 10\,11!$

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free