$8^{th}$ term of the series $2\sqrt 2 + \sqrt 2 + 0 + .....$ will be
$ - 5\sqrt 2 $
$5\sqrt 2 $
$10\sqrt 2 $
$ - 10\sqrt 2 $
If the sum of the first $2n$ terms of $2,\,5,\,8...$ is equal to the sum of the first $n$ terms of $57,\,59,\,61...$, then $n$ is equal to
${7^{th}}$ term of an $A.P.$ is $40$, then the sum of first $13$ terms is
If the sum of the series $2 + 5 + 8 + 11............$ is $60100$, then the number of terms are
If the sum of the first $n$ terms of the series $\sqrt 3 + \sqrt {75} + \sqrt {243} + \sqrt {507} + ......$ is $435\sqrt 3 $ , then $n$ equals
If $^n{C_4},{\,^n}{C_5},$ and ${\,^n}{C_6},$ are in $A.P.,$ then $n$ can be