Integral of xcos((x-pi)/3) dx
The solution
Detail solution
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Use integration by parts:
∫udv=uv−∫vdu
Let u(x)=x and let dv(x)=sin(3x+6π).
Then du(x)=1.
To find v(x):
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Let u=3x+6π.
Then let du=3dx and substitute 3du:
∫3sin(u)du
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The integral of a constant times a function is the constant times the integral of the function:
∫sin(u)du=3∫sin(u)du
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The integral of sine is negative cosine:
∫sin(u)du=−cos(u)
So, the result is: −3cos(u)
Now substitute u back in:
−3cos(3x+6π)
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:
∫(−3cos(3x+6π))dx=−3∫cos(3x+6π)dx
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Let u=3x+6π.
Then let du=3dx and substitute 3du:
∫3cos(u)du
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The integral of a constant times a function is the constant times the integral of the function:
∫cos(u)du=3∫cos(u)du
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The integral of cosine is sine:
∫cos(u)du=sin(u)
So, the result is: 3sin(u)
Now substitute u back in:
3sin(3x+6π)
So, the result is: −9sin(3x+6π)
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Add the constant of integration:
−3xcos(3x+6π)+9sin(3x+6π)+constant
The answer is:
−3xcos(3x+6π)+9sin(3x+6π)+constant
The answer (Indefinite)
[src]
/
|
| /x - pi\ /x pi\ /x pi\
| x*cos|------| dx = C + 9*sin|- + --| - 3*x*cos|- + --|
| \ 3 / \3 6 / \3 6 /
|
/
∫xcos(3x−π)dx=C−3xcos(3x+6π)+9sin(3x+6π)
The graph
9 /1 pi\ /1 pi\
- - - 3*cos|- + --| + 9*sin|- + --|
2 \3 6 / \3 6 /
−29−3cos(31+6π)+9sin(31+6π)
=
9 /1 pi\ /1 pi\
- - - 3*cos|- + --| + 9*sin|- + --|
2 \3 6 / \3 6 /
−29−3cos(31+6π)+9sin(31+6π)
-9/2 - 3*cos(1/3 + pi/6) + 9*sin(1/3 + pi/6)
Use the examples entering the upper and lower limits of integration.