Q. The value of $\frac{\int_{0}^{n}{\lbrack x\rbrack dx}}{\int_{0}^{n}{\left\{ x \right\} dx}}$ is, (where $\lbrack x\rbrack\ and\ \{ x\}$ denotes the integral part and fractional part functions of $x$ and $n \in N)$

A) $n + 2$
B) $n + 1$
C) $n$
D) $n - 1$
Explanation

(d)
$\because\ \int_{0}^{n}{\lbrack x\rbrack dx = \int_{0}^{n}{\left( x - \left\{ x \right\} \right)dx = \int_{0}^{n}{x\ dx -}\int_{0}^{n}{\left\{ x \right\} dx}}}$
$= \int_{0}^{n}{x\ dx - n}\int_{0}^{1}{\left\{ x \right\} dx}$
$= \int_{0}^{n}{x\ dx -}n\int_{0}^{1}{x\ dx} = \left( \frac{n^{2}}{2} - \frac{n}{2} \right)$
$\therefore\ \frac{\int_{0}^{n}{\lbrack x\rbrack dx}}{\int_{0}^{n}{\{ x\}}dx} = \frac{\frac{n^{2}}{2} - \frac{n}{2}}{\frac{n}{2}} = n - 1$

Dr. Abubacker
Reviewed by Dr. Abubacker

Physics Educator & NEET/JEE Specialist

Ph.D. in Physics with 19+ years of teaching experience.

Want more practice?
Practice Integrals MCQs