Integral of log^2(x)/2x dx
The solution
Detail solution
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The integral of a constant times a function is the constant times the integral of the function:
∫2xlog(x)2dx=2∫xlog(x)2dx
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Let u=log(x).
Then let du=xdx and substitute du:
∫u2e2udu
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Use integration by parts:
∫udv=uv−∫vdu
Let u(u)=u2 and let dv(u)=e2u.
Then du(u)=2u.
To find v(u):
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There are multiple ways to do this integral.
Method #1
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Let u=2u.
Then let du=2du and substitute 2du:
∫4eudu
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The integral of a constant times a function is the constant times the integral of the function:
∫2eudu=2∫eudu
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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
Method #2
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Let u=e2u.
Then let du=2e2udu and substitute 2du:
∫41du
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The integral of a constant times a function is the constant times the integral of the function:
∫21du=2∫1du
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The integral of a constant is the constant times the variable of integration:
∫1du=u
So, the result is: 2u
Now substitute u back in:
2e2u
Now evaluate the sub-integral.
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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):
-
Let u=2u.
Then let du=2du and substitute 2du:
∫4eudu
-
The integral of a constant times a function is the constant times the integral of the function:
∫2eudu=2∫eudu
-
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.
-
The integral of a constant times a function is the constant times the integral of the function:
∫2e2udu=2∫e2udu
-
Let u=2u.
Then let du=2du and substitute 2du:
∫4eudu
-
The integral of a constant times a function is the constant times the integral of the function:
∫2eudu=2∫eudu
-
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:
2x2log(x)2−2x2log(x)+4x2
So, the result is: 4x2log(x)2−4x2log(x)+8x2
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Now simplify:
8x2⋅(2log(x)2−2log(x)+1)
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Add the constant of integration:
8x2⋅(2log(x)2−2log(x)+1)+constant
The answer is:
8x2⋅(2log(x)2−2log(x)+1)+constant
The answer (Indefinite)
[src]
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|
| 2 2 2 2 2
| log (x)*x x x *log(x) x *log (x)
| --------- dx = C + -- - --------- + ----------
| 2 8 4 4
|
/
∫2xlog(x)2dx=C+4x2log(x)2−4x2log(x)+8x2
The graph
−81+8e2
=
−81+8e2
Use the examples entering the upper and lower limits of integration.