InterviewSolution
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InterviewSolution
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`int(1+x)/(x+e^(-x))dx` is equal toA. `log|(x-e^(-x))|+C`B. `log|(x+e^(-x))|+C`C. `log|(1+xe^(x))|+C`D. `(1+xe^(x))^(2)+C` |
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Answer» Correct Answer - C Let `l=int(1+x)/(x+e^(-x))dx=int(e^(x)(1+x))/(xe^(x)+1)dx` Put`" "xe^(x)+1=t` `rArr" "(xe^(x)+e^(x))dx=dt` `rArr" "(x+1)e^(x)dx=dt` `therefore" "l=int(dt)/(dt)=log|t|+C` `=log|(xe^(x)+1)|+C` |
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