1.

Evaluate: `int(2"x"dot"tan"^(-1)x)/(1+"x"^4)" dx"`A. `(tan^(-1)x^(2))^(2)+C`B. `2tan^(-1)x^(2)+C`C. `(1)/(2)(tan^(-1)x^(2))^(2)+C`D. none of these

Answer» Correct Answer - C
Put `tan^(-1)x^(2)=t and(2x)/((1+x^(4)))dx=dt`.
`:." "I=tdt=(t^(2))/(2)+C=(1)/(2)(tan^(-1)x^(2))^(2)+C`.


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