Definite Integration Question 107

Question: $ \int_0^{2a}{\frac{f(x)}{f(x)+f(2a-x)}dx=} $

[IIT 1988; Karnataka CET 2000]

Options:

A) $ a $

B) $ \frac{a}{2} $

C) $ 2a $

D) 0

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Answer:

Correct Answer: A

Solution:

$ I=\int_0^{2a}{\frac{f(x)}{f(x)+f(2a-x)}dx} $ ……(i)

$ I=\int_0^{2a}{\frac{f(2a-x)}{f(2a-x)+f(x)}}dx $ ……(ii)

Adding (i) and (ii), we get $ 2I=\int_0^{2a}{dx=2a\Rightarrow I=a} $ .