数学试题讲解

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设

I = \int \arctan x d x

, 则

I =

x \arctan x - \ln \sqrt{x^{2} + 1} + C

x \arctan x - \ln | x^{2} + 1 | + C

x \arctan x + \frac{1}{2} (x^{2} + 1) + C

. D.

\frac{1}{1 + x^{2}} + C