The sum of the series $\frac{1}{2} + \frac{1}{3} + \frac{1}{6} + ........$ to $9$ terms is
$ - \frac{5}{6}$
$ - \frac{1}{2}$
$1$
$ - \frac{3}{2}$
Let the sequence ${a_1},{a_2},{a_3},.............{a_{2n}}$ form an $A.P. $ Then $a_1^2 - a_2^2 + a_3^3 - ......... + a_{2n - 1}^2 - a_{2n}^2 = $
If the sum and product of the first three term in an $A.P$. are $33$ and $1155$, respectively, then a value of its $11^{th}$ tern is
$8^{th}$ term of the series $2\sqrt 2 + \sqrt 2 + 0 + .....$ will be
The sum of $n$ arithmetic means between $a$ and $b$, is
If ${m^{th}}$ terms of the series $63 + 65 + 67 + 69 + .........$ and $3 + 10 + 17 + 24 + ......$ be equal, then $m = $