Proof Of The Derivative Of Arccotan(x)

What we are trying to find is:

\[ \int \operatorname{arccot}(x) \ dx \]

We are going to use integration by parts:

\[ \int u \ dv = uv - \int v \ du\]

Let's define \(u\) and \(v\):

\[\begin{gathered} u = \operatorname{arccot}(x), du= - \frac{dx}{x^2 +1} \\ v = x , dv = dx \end{gathered}\]

This means:

\[ \int \operatorname{arccot}(x) \ dx = x(\operatorname{arccot}(x)) - \int - \frac{x}{x^2 +1} \ dx\]

The derivative of \(\ln(x^2 +1)\) is \(\frac{1}{x^2 +1} *2x\), this means:

\[ \int \operatorname{arccot}(x) \ dx = x(\operatorname{arccot}(x)) + \frac{\ln(x^2 +1)}{2} + C\]

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