Integral Calculus Question 179

Question: $ \int_{{}}^{{}}{\frac{(x+1){{(x+\log x)}^{2}}}{x}dx=} $

[AI CBSE 1986]

Options:

A) $ \frac{1}{3}(x+\log x)+c $

B) $ \frac{1}{3}{{(x+\log x)}^{2}}+c $

C) $ \frac{1}{3}{{(x+\log x)}^{3}}+c $

D) None of these

Show Answer

Answer:

Correct Answer: C

Solution:

Put $ t=x+\log x\Rightarrow dt=( 1+\frac{1}{x} ),dx, $ then $ \int_{{}}^{{}}{\frac{(x+1){{(x+\log x)}^{2}}}{x},dx}=\int_{{}}^{{}}{t^{2}dt}=\frac{t^{3}}{3}+c $ $ =\frac{1}{3}{{(x+\log x)}^{3}}+c. $