Definite Integration Question 404

Question: $ \int_1^{e}{\frac{1+\log x}{x}dx=} $

[SCRA 1986]

Options:

A) $ \frac{3}{2} $

B) $ \frac{1}{2} $

C) $ \frac{1}{e} $

D) None of these

Show Answer

Answer:

Correct Answer: A

Solution:

$ I=\int_1^{e}{\frac{1+\log x}{x}}dx=\int_1^{e}{\frac{1}{x}dx+\int_1^{e}{\frac{\log x}{x}dx}} $

therefore $ [{\log _{e}}x]_1^{e}+[ \frac{{{(\log x)}^{2}}}{2} ]_1^{e}=\frac{3}{2} $ .