Functions 3 Question 9

9. Let $F(x)$ be an indefinite integral of $\sin ^{2} x$.

Statement I The function $F(x)$ satisfies

$F(x+\pi)=F(x)$ for all real $x$.

Because

Statement II $\sin ^{2}(x+\pi)=\sin ^{2} x$, for all real $x$.

$(2007,3 M)$

Analytical & Descriptive Question

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Answer:

Correct Answer: 9. (d)

Solution:

  1. Let $\varphi(x)=f(x)-g(x)=\begin{array}{ll}x, & x \in Q \ -x, & x \notin Q\end{array}$

Now, to check one-one.

Take any straight line parallel to $X$-axis which will intersect $\varphi(x)$ only at one point.

$\Rightarrow \varphi(x)$ is one-one.

To check onto

As $\quad f(x)=\begin{array}{cc}x, & x \in Q \ -x, & x \notin Q\end{array}$, which shows

$y=x$ and $y=-x$ for rational and irrational values

$\Rightarrow y \in$ real numbers.

$$ \therefore \quad \text { Range }=\text { Codomain } \Rightarrow \text { onto } $$

Thus, $f-g$ is one-one and onto.



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