Integral Calculus Question 53

Question: To find the value of $ \int_{{}}^{{}}{\frac{1+\log x}{x}}dx $ , the proper substitution is

[MP PET 1988]

Options:

A) $ \log x=t $

B) $ 1+\log x=t $

C) $ \frac{1}{x}=t $

D) None of these

Show Answer

Answer:

Correct Answer: B

Solution:

Let $ 1+\log x=t\Rightarrow \frac{1}{x},dx=dt $ Therefore, $ \int_{{}}^{{}}{\frac{1+\log x}{x}},dx=\int_{{}}^{{}}{t,dt}=\frac{t^{2}}{2} $ $ =\frac{{{(1+\log x)}^{2}}}{2} $ .