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The value of the integral  \mathrm \int_{-2}^{2} \frac{\left|x^{3}+x\right|}{\left({e}^{x|x|}+1\right)} \mathrm{d} x is equal to :

 

Option: 1

5 \mathrm{e}^{2}


Option: 2

3 \mathrm{e}^{-2}


Option: 3

4


Option: 4

6


Answers (1)

best_answer

\mathrm{I=\int_{-2}^{2} \frac{\left|x^{3}+x\right|}{e^{x|x|}+1} d x}                .............(1)

\mathrm{I(x)=I(a+b-x)} \\

\mathrm{\Rightarrow I =\int_{-2}^{2} \frac{\left|-x^{3}-x\right|}{e^{-x|-x|}+1} d x }\\

\mathrm{=\int_{-2}^{2} \frac{\left|x^{3}+x\right|}{e^{-x|x|}+1}=\int_{-2}^{2} \frac{e^{x|x|}\left|x^{3}+x\right|}{e^{x|x|}+1}dx}               ............(2)

Add eqn (1) and (2)

\mathrm{\Rightarrow 2 I =\int_{-2}^{2}\left|x^{3}+x\right| d x=2 \int_{0}^{2}\left|x^{3}+x\right| d x }\\

\mathrm{ \Rightarrow I=\int_{0}^{2}\left(x^{3}+x\right) d x=6}

Hence the correct aswer is option 4.

Posted by

Sanket Gandhi

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