Integral of (x^2-3x)lnxdx 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).
Then let du=xdx and substitute du:
∫(ue3u−3ue2u)du
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Integrate term-by-term:
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Use integration by parts:
∫udv=uv−∫vdu
Let u(u)=u and let dv(u)=e3u.
Then du(u)=1.
To find v(u):
-
Let u=3u.
Then let du=3du and substitute 3du:
∫3eudu
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The integral of a constant times a function is the constant times the integral of the function:
-
The integral of the exponential function is itself.
∫eudu=eu
So, the result is: 3eu
Now substitute u back in:
3e3u
Now evaluate the sub-integral.
-
The integral of a constant times a function is the constant times the integral of the function:
∫3e3udu=3∫e3udu
-
Let u=3u.
Then let du=3du and substitute 3du:
∫3eudu
-
The integral of a constant times a function is the constant times the integral of the function:
-
The integral of the exponential function is itself.
∫eudu=eu
So, the result is: 3eu
Now substitute u back in:
3e3u
So, the result is: 9e3u
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The integral of a constant times a function is the constant times the integral of the function:
∫(−3ue2u)du=−3∫ue2udu
-
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:
∫2eudu
-
The integral of a constant times a function is the constant times the integral of the function:
-
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:
∫2eudu
-
The integral of a constant times a function is the constant times the integral of the function:
-
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
So, the result is: −23ue2u+43e2u
The result is: 3ue3u−23ue2u−9e3u+43e2u
Now substitute u back in:
3x3log(x)−9x3−23x2log(x)+43x2
Method #2
-
Rewrite the integrand:
(x2−3x)log(x)=x2log(x)−3xlog(x)
-
Integrate term-by-term:
-
Let u=log(x).
Then let du=xdx and substitute du:
∫ue3udu
-
Use integration by parts:
∫udv=uv−∫vdu
Let u(u)=u and let dv(u)=e3u.
Then du(u)=1.
To find v(u):
-
Let u=3u.
Then let du=3du and substitute 3du:
∫3eudu
-
The integral of a constant times a function is the constant times the integral of the function:
-
The integral of the exponential function is itself.
∫eudu=eu
So, the result is: 3eu
Now substitute u back in:
3e3u
Now evaluate the sub-integral.
-
The integral of a constant times a function is the constant times the integral of the function:
∫3e3udu=3∫e3udu
-
Let u=3u.
Then let du=3du and substitute 3du:
∫3eudu
-
The integral of a constant times a function is the constant times the integral of the function:
-
The integral of the exponential function is itself.
∫eudu=eu
So, the result is: 3eu
Now substitute u back in:
3e3u
So, the result is: 9e3u
Now substitute u back in:
3x3log(x)−9x3
-
The integral of a constant times a function is the constant times the integral of the function:
∫(−3xlog(x))dx=−3∫xlog(x)dx
-
Let u=log(x).
Then let du=xdx and substitute du:
∫ue2udu
-
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:
∫2eudu
-
The integral of a constant times a function is the constant times the integral of the function:
-
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:
∫2eudu
-
The integral of a constant times a function is the constant times the integral of the function:
-
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)−4x2
So, the result is: −23x2log(x)+43x2
The result is: 3x3log(x)−9x3−23x2log(x)+43x2
Method #3
-
Use integration by parts:
∫udv=uv−∫vdu
Let u(x)=log(x) and let dv(x)=x2−3x.
Then du(x)=x1.
To find v(x):
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Rewrite the integrand:
x(x−3)=x2−3x
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Integrate term-by-term:
-
The integral of xn is n+1xn+1 when n=−1:
∫x2dx=3x3
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The integral of a constant times a function is the constant times the integral of the function:
∫(−3x)dx=−3∫xdx
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The integral of xn is n+1xn+1 when n=−1:
∫xdx=2x2
So, the result is: −23x2
The result is: 3x3−23x2
Now evaluate the sub-integral.
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Rewrite the integrand:
x3x3−23x2=3x2−23x
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Integrate term-by-term:
-
The integral of a constant times a function is the constant times the integral of the function:
∫3x2dx=3∫x2dx
-
The integral of xn is n+1xn+1 when n=−1:
∫x2dx=3x3
So, the result is: 9x3
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The integral of a constant times a function is the constant times the integral of the function:
∫(−23x)dx=−23∫xdx
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The integral of xn is n+1xn+1 when n=−1:
∫xdx=2x2
So, the result is: −43x2
The result is: 9x3−43x2
Method #4
-
Rewrite the integrand:
(x2−3x)log(x)=x2log(x)−3xlog(x)
-
Integrate term-by-term:
-
Let u=log(x).
Then let du=xdx and substitute du:
∫ue3udu
-
Use integration by parts:
∫udv=uv−∫vdu
Let u(u)=u and let dv(u)=e3u.
Then du(u)=1.
To find v(u):
-
Let u=3u.
Then let du=3du and substitute 3du:
∫3eudu
-
The integral of a constant times a function is the constant times the integral of the function:
-
The integral of the exponential function is itself.
∫eudu=eu
So, the result is: 3eu
Now substitute u back in:
3e3u
Now evaluate the sub-integral.
-
The integral of a constant times a function is the constant times the integral of the function:
∫3e3udu=3∫e3udu
-
Let u=3u.
Then let du=3du and substitute 3du:
∫3eudu
-
The integral of a constant times a function is the constant times the integral of the function:
-
The integral of the exponential function is itself.
∫eudu=eu
So, the result is: 3eu
Now substitute u back in:
3e3u
So, the result is: 9e3u
Now substitute u back in:
3x3log(x)−9x3
-
The integral of a constant times a function is the constant times the integral of the function:
∫(−3xlog(x))dx=−3∫xlog(x)dx
-
Let u=log(x).
Then let du=xdx and substitute du:
∫ue2udu
-
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:
∫2eudu
-
The integral of a constant times a function is the constant times the integral of the function:
-
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:
∫2eudu
-
The integral of a constant times a function is the constant times the integral of the function:
-
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)−4x2
So, the result is: −23x2log(x)+43x2
The result is: 3x3log(x)−9x3−23x2log(x)+43x2
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Now simplify:
36x2(12xlog(x)−4x−54log(x)+27)
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Add the constant of integration:
36x2(12xlog(x)−4x−54log(x)+27)+constant
The answer is:
36x2(12xlog(x)−4x−54log(x)+27)+constant
The answer (Indefinite)
[src]
/
| 3 2 2 3
| / 2 \ x 3*x 3*x *log(x) x *log(x)
| \x - 3*x/*log(x) dx = C - -- + ---- - ----------- + ---------
| 9 4 2 3
/
∫(x2−3x)log(x)dx=C+3x3log(x)−9x3−23x2log(x)+43x2
The graph
Use the examples entering the upper and lower limits of integration.