Integral of log(1+x)/sqrt(1+x) 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(x+1).
Then let du=x+1dx and substitute du:
∫ue2udu
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Use integration by parts:
∫udv=uv−∫vdu
Let u(u)=u and let dv(u)=e2u.
Then du(u)=1.
To find v(u):
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Let u=2u.
Then let du=2du and substitute 2du:
∫2eudu
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The integral of a constant times a function is the constant times the integral of the function:
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The integral of the exponential function is itself.
∫eudu=eu
So, the result is: 2eu
Now substitute u back in:
2e2u
Now evaluate the sub-integral.
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The integral of a constant times a function is the constant times the integral of the function:
∫2e2udu=2∫e2udu
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Let u=2u.
Then let du=2du and substitute 2du:
∫2eudu
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The integral of a constant times a function is the constant times the integral of the function:
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The integral of the exponential function is itself.
∫eudu=eu
So, the result is: 2eu
Now substitute u back in:
2e2u
So, the result is: 4e2u
Now substitute u back in:
2x+1log(x+1)−4x+1
Method #2
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Use integration by parts:
∫udv=uv−∫vdu
Let u(x)=log(x+1) and let dv(x)=x+11.
Then du(x)=x+11.
To find v(x):
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Let u=x+1.
Then let du=dx and substitute du:
∫u1du
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The integral of un is n+1un+1 when n=−1:
∫u1du=2u
Now substitute u back in:
Now evaluate the sub-integral.
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The integral of a constant times a function is the constant times the integral of the function:
∫x+12dx=2∫x+11dx
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Let u=x+1.
Then let du=dx and substitute du:
∫u1du
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The integral of un is n+1un+1 when n=−1:
∫u1du=2u
Now substitute u back in:
So, the result is: 4x+1
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Now simplify:
2x+1(log(x+1)−2)
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Add the constant of integration:
2x+1(log(x+1)−2)+constant
The answer is:
2x+1(log(x+1)−2)+constant
The answer (Indefinite)
[src]
/
|
| log(1 + x) _______ _______
| ---------- dx = C - 4*\/ 1 + x + 2*\/ 1 + x *log(1 + x)
| _______
| \/ 1 + x
|
/
∫x+1log(x+1)dx=C+2x+1log(x+1)−4x+1
The graph
−4+4log(4)
=
−4+4log(4)
Use the examples entering the upper and lower limits of integration.