Integral of (3x+4)*e^(3x) 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=3x.
Then let du=3dx and substitute du:
∫(3ueu+34eu)du
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Integrate term-by-term:
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The integral of a constant times a function is the constant times the integral of the function:
∫3ueudu=3∫ueudu
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Use integration by parts:
∫udv=uv−∫vdu
Let u(u)=u and let dv(u)=eu.
Then du(u)=1.
To find v(u):
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The integral of the exponential function is itself.
∫eudu=eu
Now evaluate the sub-integral.
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The integral of the exponential function is itself.
∫eudu=eu
So, the result is: 3ueu−3eu
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The integral of a constant times a function is the constant times the integral of the function:
∫34eudu=34∫eudu
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The integral of the exponential function is itself.
∫eudu=eu
So, the result is: 34eu
The result is: 3ueu+eu
Now substitute u back in:
xe3x+e3x
Method #2
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Rewrite the integrand:
e3x(3x+4)=3xe3x+4e3x
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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:
∫3xe3xdx=3∫xe3xdx
-
Use integration by parts:
∫udv=uv−∫vdu
Let u(x)=x and let dv(x)=e3x.
Then du(x)=1.
To find v(x):
-
Let u=3x.
Then let du=3dx 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:
3e3x
Now evaluate the sub-integral.
-
The integral of a constant times a function is the constant times the integral of the function:
∫3e3xdx=3∫e3xdx
-
Let u=3x.
Then let du=3dx 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:
3e3x
So, the result is: 9e3x
So, the result is: xe3x−3e3x
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The integral of a constant times a function is the constant times the integral of the function:
∫4e3xdx=4∫e3xdx
-
Let u=3x.
Then let du=3dx 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:
3e3x
So, the result is: 34e3x
The result is: xe3x+e3x
Method #3
-
Rewrite the integrand:
e3x(3x+4)=3xe3x+4e3x
-
Integrate term-by-term:
-
The integral of a constant times a function is the constant times the integral of the function:
∫3xe3xdx=3∫xe3xdx
-
Use integration by parts:
∫udv=uv−∫vdu
Let u(x)=x and let dv(x)=e3x.
Then du(x)=1.
To find v(x):
-
Let u=3x.
Then let du=3dx 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:
3e3x
Now evaluate the sub-integral.
-
The integral of a constant times a function is the constant times the integral of the function:
∫3e3xdx=3∫e3xdx
-
Let u=3x.
Then let du=3dx 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:
3e3x
So, the result is: 9e3x
So, the result is: xe3x−3e3x
-
The integral of a constant times a function is the constant times the integral of the function:
∫4e3xdx=4∫e3xdx
-
Let u=3x.
Then let du=3dx 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:
3e3x
So, the result is: 34e3x
The result is: xe3x+e3x
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Now simplify:
(x+1)e3x
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Add the constant of integration:
(x+1)e3x+constant
The answer is:
(x+1)e3x+constant
The answer (Indefinite)
[src]
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| 3*x 3*x 3*x
| (3*x + 4)*E dx = C + x*e + e
|
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∫e3x(3x+4)dx=C+xe3x+e3x
The graph
Use the examples entering the upper and lower limits of integration.