$8^{th}$ 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 ${S_n}$ denotes the sum of $n$ terms of an arithmetic progression, then the value of $({S_{2n}} - {S_n})$ is equal to
Let $S_n$ denote the sum of the first $n$ terms of an $A.P$.. If $S_4 = 16$ and $S_6 = -48$, then $S_{10}$ is equal to
${7^{th}}$ term of an $A.P.$ is $40$, then the sum of first $13$ terms is
If $n$ be odd or even, then the sum of $n$ terms of the series $1 - 2 + $ $3 - $$4 + 5 - 6 + ......$ will be
The sum of all natural numbers between $1$ and $100$ which are multiples of $3$ is