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Integral of x^2*e^(-x)*dx dx
The solution
Detail solution
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Use integration by parts:
∫udv=uv−∫vdu
Let u(x)=x2 and let dv(x)=e−x.
Then du(x)=2x.
To find v(x):
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There are multiple ways to do this integral.
Method #1
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Let u=−x.
Then let du=−dx and substitute −du:
∫eudu
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The integral of a constant times a function is the constant times the integral of the function:
∫(−eu)du=−∫eudu
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The integral of the exponential function is itself.
∫eudu=eu
So, the result is: −eu
Now substitute u back in:
Method #2
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Let u=e−x.
Then let du=−e−xdx and substitute −du:
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The integral of a constant times a function is the constant times the integral of the function:
∫(−1)du=−∫1du
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The integral of a constant is the constant times the variable of integration:
∫1du=u
So, the result is: −u
Now substitute u back in:
Now evaluate the sub-integral.
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Use integration by parts:
∫udv=uv−∫vdu
Let u(x)=−2x and let dv(x)=e−x.
Then du(x)=−2.
To find v(x):
-
Let u=−x.
Then let du=−dx and substitute −du:
∫eudu
-
The integral of a constant times a function is the constant times the integral of the function:
∫(−eu)du=−∫eudu
-
The integral of the exponential function is itself.
∫eudu=eu
So, the result is: −eu
Now substitute u back in:
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:
∫2e−xdx=2∫e−xdx
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Let u=−x.
Then let du=−dx and substitute −du:
∫eudu
-
The integral of a constant times a function is the constant times the integral of the function:
∫(−eu)du=−∫eudu
-
The integral of the exponential function is itself.
∫eudu=eu
So, the result is: −eu
Now substitute u back in:
So, the result is: −2e−x
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Now simplify:
(−x2−2x−2)e−x
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Add the constant of integration:
(−x2−2x−2)e−x+constant
The answer is:
(−x2−2x−2)e−x+constant
The answer (Indefinite)
[src]
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| 2 -x -x 2 -x -x
| x *e *1 dx = C - 2*e - x *e - 2*x*e
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(−x2−2x−2)e−x
The graph
2−5e−1
=
Use the examples entering the upper and lower limits of integration.