Integral of log(atan(x))/(1+x^2) dx
The solution
Detail solution
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There are multiple ways to do this integral.
Method #1
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Let u=log(atan(x)).
Then let du=(x2+1)atan(x)dx and substitute du:
∫ueudu
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Use integration by parts:
∫udv=uv−∫vdu
Let u(u)=u and let dv(u)=eu.
Then du(u)=1.
To find v(u):
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The integral of the exponential function is itself.
∫eudu=eu
Now evaluate the sub-integral.
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The integral of the exponential function is itself.
∫eudu=eu
Now substitute u back in:
log(atan(x))atan(x)−atan(x)
Method #2
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Use integration by parts:
∫udv=uv−∫vdu
Let u(x)=log(atan(x)) and let dv(x)=x2+11.
Then du(x)=(x2+1)atan(x)1.
To find v(x):
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The integral of x2+11 is atan(x).
Now evaluate the sub-integral.
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The integral of x2+11 is atan(x).
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Now simplify:
(log(atan(x))−1)atan(x)
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Add the constant of integration:
(log(atan(x))−1)atan(x)+constant
The answer is:
(log(atan(x))−1)atan(x)+constant
The answer (Indefinite)
[src]
/
|
| log(atan(x))
| ------------ dx = C - atan(x) + atan(x)*log(atan(x))
| 2
| 1 + x
|
/
arctanxlogarctanx−arctanx
/pi\
pi*log|--|
pi \4 /
- -- + ----------
4 4
4πlog(4π)−4π
=
/pi\
pi*log|--|
pi \4 /
- -- + ----------
4 4
−4π+4πlog(4π)
Use the examples entering the upper and lower limits of integration.