1.

` int_(-1)^(1)log(x+sqrt(x^(2)+1))` dx is equal to

Answer» Correct Answer - A
Let f(x) = log `(x+sqrt(1+x^(2)))`and replacing x by -x , we get
` f(-x) = log (sqrt(1+x^(2))-x)`
` = log [ (sqrt(1+x^(2))-x) ((sqrt(1+x^(2))+x))/((sqrt(1+x^(2))+x))]`
` = log. ([ (1+x^(2))-x^(2)])/((sqrt(1+x^(2))+x))= log 1 - log (sqrt(1+x^(2))+x)`
` = - log (sqrt(1+x^(2))+x)=f(x)`
Hence, f(x) is an odd function .
` :. int _(-1)^(1) log (x+sqrt(1+x^(2)))dx = 0 `


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