Q. The value of $\int_{- 1}^{1}{\lbrack x\lbrack 1 + \sin{\pi x\rbrack\ dx}}$ is ($\lbrack \bullet \rbrack$ denotes the greatest integer)

A) 2
B) 0
C) 1
D) None of these
Explanation

(a)
$\int_{- 1}^{1}{\lbrack x\lbrack 1 + \sin{\pi x\rbrack + 1\rbrack dx}}$
$= \int_{- 1}^{0}{\lbrack x\lbrack 1 + \sin{\pi x\rbrack + 1\rbrack dx + \int_{0}^{1}{\lbrack x\lbrack 1 + \sin{\pi x\rbrack + 1\rbrack dx}}}}$
Now, $- 1 < x < 0\ \ \Rightarrow \ \lbrack 1 + \sin{\pi x\rbrack = 0}$
$0 < x < 1\ \ \Rightarrow \ \lbrack 1 + \sin{\pi x\rbrack = 1}$
$\Rightarrow \ \lbrack x\lbrack 1 + \sin{\pi x\rbrack + 1\rbrack = 1}$
$\therefore\ \int_{- 1}^{1}{\lbrack x\lbrack 1 + \sin{\pi x\rbrack + 1\rbrack dx = 2}}$

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