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Integral of x^3*e^(x/3) dx
The solution
Detail solution
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Use integration by parts:
∫udv=uv−∫vdu
Let u(x)=x3 and let dv(x)=e3x.
Then du(x)=3x2.
To find v(x):
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There are multiple ways to do this integral.
Method #1
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Let u=3x.
Then let du=3dx and substitute 3du:
∫9eudu
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The integral of a constant times a function is the constant times the integral of the function:
∫3eudu=3∫eudu
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The integral of the exponential function is itself.
∫eudu=eu
So, the result is: 3eu
Now substitute u back in:
3e3x
Method #2
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Let u=e3x.
Then let du=3e3xdx and substitute 3du:
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The integral of a constant times a function is the constant times the integral of the function:
∫3du=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:
3e3x
Now evaluate the sub-integral.
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Use integration by parts:
∫udv=uv−∫vdu
Let u(x)=9x2 and let dv(x)=e3x.
Then du(x)=18x.
To find v(x):
-
Let u=3x.
Then let du=3dx 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:
3e3x
Now evaluate the sub-integral.
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Use integration by parts:
∫udv=uv−∫vdu
Let u(x)=54x and let dv(x)=e3x.
Then du(x)=54.
To find v(x):
-
Let u=3x.
Then let du=3dx 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:
3e3x
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:
∫162e3xdx=162∫e3xdx
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Let u=3x.
Then let du=3dx 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:
3e3x
So, the result is: 486e3x
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Now simplify:
3(x3−9x2+54x−162)e3x
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Add the constant of integration:
3(x3−9x2+54x−162)e3x+constant
The answer is:
3(x3−9x2+54x−162)e3x+constant
The answer (Indefinite)
[src]
/
|
| x x x x x
| - - - - -
| 3 3 3 2 3 3 3 3
| x *e dx = C - 486*e - 27*x *e + 3*x *e + 162*x*e
|
/
(3x3−27x2+162x−486)e3x
The graph
486−348e31
=
486−348e31
Use the examples entering the upper and lower limits of integration.