Practicing Success

Target Exam

CUET

Subject

-- Mathematics - Section B1

Chapter

Definite Integration

Question:

Statement-1: $\int\limits\limits_0^{n \pi+v}|\sin x| d x=2 n+1-\cos v$ where $n \in N$ and $0 \leq v<\pi$.

Statement-2: If $f(x)$ is a periodic function with period $T$, then

(i) $\int\limits_0^{n T} f(x) d x=n \int\limits_0^T f(x) d x$, where $n \in N$ and

(ii) $\int\limits_{n T}^{n t+a} f(x) d x=\int\limits_0^a f(x) d x$, where $n \in N$

Options:

Statement-1 is True, Statement-2 is True; Statement-2 is a correct explanation for Statement-1.

Statement-1 is True, Statement-2 is True; Statement-2 is not a correct explanation for Statement-1.

Statement-1 is True, Statement-2 is False.

Statement-1 is False, Statement-2 is True.

Correct Answer:

Statement-1 is True, Statement-2 is True; Statement-2 is a correct explanation for Statement-1.

Explanation:

Clearly, statement-2 is true.

Now,

$\int\limits_0^{n \pi+v}|\sin x| d x$

$=\int\limits_0^{n \pi}|\sin x| d x+\int\limits_{n \pi}^{n \pi+v}|\sin x| d x$

$=n \int\limits_0^\pi|\sin x| d x+\int\limits_0^v|\sin x| d x$

$=n \int\limits_0^\pi \sin x d x+\int\limits_0^v \sin x d x$

$[∵ 0<\sin x<1$ for $x \in(0, \pi)]$

$=2 n+1-\cos v=(2 n+1)-\cos v$

So, statement- 1 is also true and statement-2 is a correct explanation for statement-1.