Integral of (x^2+2x)lnx 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+2ue2u)du
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Integrate term-by-term:
-
Use integration by parts:
∫udv=uv−∫vdu
Let u(u)=u and let dv(u)=e3u.
Then du(u)=1.
To find v(u):
-
There are multiple ways to do this integral.
Method #1
-
Let u=3u.
Then let du=3du and substitute 3du:
∫9eudu
-
The integral of a constant times a function is the constant times the integral of the function:
∫3eudu=3∫eudu
-
The integral of the exponential function is itself.
∫eudu=eu
So, the result is: 3eu
Now substitute u back in:
3e3u
Method #2
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Let u=e3u.
Then let du=3e3udu and substitute 3du:
∫91du
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The integral of a constant times a function is the constant times the integral of the function:
∫31du=3∫1du
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The integral of a constant is the constant times the variable of integration:
∫1du=u
So, the result is: 3u
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:
∫9eudu
-
The integral of a constant times a function is the constant times the integral of the function:
∫3eudu=3∫eudu
-
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
-
The integral of a constant times a function is the constant times the integral of the function:
∫2ue2udu=2∫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:
∫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
So, the result is: ue2u−2e2u
The result is: 3ue3u+ue2u−9e3u−2e2u
Now substitute u back in:
3x3log(x)−9x3+x2log(x)−2x2
Method #2
-
Rewrite the integrand:
(x2+2x)log(x)=x2log(x)+2xlog(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:
∫9eudu
-
The integral of a constant times a function is the constant times the integral of the function:
∫3eudu=3∫eudu
-
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:
∫9eudu
-
The integral of a constant times a function is the constant times the integral of the function:
∫3eudu=3∫eudu
-
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:
∫2xlog(x)dx=2∫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:
∫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)−4x2
So, the result is: x2log(x)−2x2
The result is: 3x3log(x)−9x3+x2log(x)−2x2
Method #3
-
Use integration by parts:
∫udv=uv−∫vdu
Let u(x)=log(x) and let dv(x)=x2+2x.
Then du(x)=x1.
To find v(x):
-
Rewrite the integrand:
x(x+2)=x2+2x
-
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:
∫2xdx=2∫xdx
-
The integral of xn is n+1xn+1 when n=−1:
∫xdx=2x2
So, the result is: x2
The result is: 3x3+x2
Now evaluate the sub-integral.
-
Rewrite the integrand:
x3x3+x2=3x2+x
-
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
-
The integral of xn is n+1xn+1 when n=−1:
∫xdx=2x2
The result is: 9x3+2x2
Method #4
-
Rewrite the integrand:
(x2+2x)log(x)=x2log(x)+2xlog(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:
∫9eudu
-
The integral of a constant times a function is the constant times the integral of the function:
∫3eudu=3∫eudu
-
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:
∫9eudu
-
The integral of a constant times a function is the constant times the integral of the function:
∫3eudu=3∫eudu
-
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:
∫2xlog(x)dx=2∫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:
∫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)−4x2
So, the result is: x2log(x)−2x2
The result is: 3x3log(x)−9x3+x2log(x)−2x2
-
Now simplify:
x2(3xlog(x)−9x+log(x)−21)
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Add the constant of integration:
x2(3xlog(x)−9x+log(x)−21)+constant
The answer is:
x2(3xlog(x)−9x+log(x)−21)+constant
The answer (Indefinite)
[src]
/
| 2 3 3
| / 2 \ x x 2 x *log(x)
| \x + 2*x/*log(x) dx = C - -- - -- + x *log(x) + ---------
| 2 9 3
/
(3x3+x2)logx−182x3+9x2
−1811
=
−1811
Use the examples entering the upper and lower limits of integration.