A series whose $n^{th}$ term is $\left( {\frac{n}{x}} \right) + y,$ the sum of $r$ terms will be
$\left\{ {\frac{{r(r + 1)}}{{2x}}} \right\} + ry$
$\left\{ {\frac{{r(r - 1)}}{{2x}}} \right\}$
$\left\{ {\frac{{r(r - 1)}}{{2x}}} \right\} - ry$
$\left\{ {\frac{{r(r + 1)}}{{2y}}} \right\} - rx$
If ${\log _5}2,\,{\log _5}({2^x} - 3)$ and ${\log _5}(\frac{{17}}{2} + {2^{x - 1}})$ are in $A.P.$ then the value of $x$ is :-
The sum of integers from $1$ to $100$ that are divisible by $2$ or $5$ is
The sum of $n$ terms of two arithmetic progressions are in the ratio $(3 n+8):(7 n+15) .$ Find the ratio of their $12^{\text {th }}$ terms.
If $\log _e \mathrm{a}, \log _e \mathrm{~b}, \log _e \mathrm{c}$ are in an $A.P.$ and $\log _e \mathrm{a}-$ $\log _e 2 b, \log _e 2 b-\log _e 3 c, \log _e 3 c-\log _e a$ are also in an $A.P,$ then $a: b: c$ is equal to
Write the first five terms of the sequences whose $n^{t h}$ term is $a_{n}=\frac{n}{n+1}$