MCQ
Let $f$ be a function such that $f(x)\, = \,\sum\limits_{n\, - \,1}^n {\left[ {r\, + \,\cos \frac{x}{r}} \right]} $ where [.] denotes greatest integer function and $x \in [0,\pi]$, then range of $f(x)$ is-
- A$\left[ {0\,,\,\frac{{n(n\, + \,1)}}{2}} \right]$
- ✓$\left\{ {\frac{{{n^2}\, + \,n\, - \,2}}{2}\,,\,\frac{{{n^2}\, + \,3n}}{2}\,,\,\frac{{{n^{2\,}} + \,n}}{2}} \right\}$
- C$\left\{ {\frac{{{n^2}\, - \,n\,}}{2}\,,\,\frac{{{n^2}\, + \,3n}}{2}} \right\}$
- D$\left[ {\frac{{{n^2}\, - \,n\,}}{2}\,,\,\frac{{{n^2}\, + \,3n}}{2}} \right]$