Integral of (2-x)sinx/2 dx
The solution
Detail solution
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The integral of a constant times a function is the constant times the integral of the function:
∫2(2−x)sin(x)dx=2∫(2−x)sin(x)dx
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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:
∫(usin(u)+2sin(u))du
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Integrate term-by-term:
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Use integration by parts:
∫udv=uv−∫vdu
Let u(u)=u and let dv(u)=sin(u).
Then du(u)=1.
To find v(u):
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The integral of sine is negative cosine:
∫sin(u)du=−cos(u)
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:
∫(−cos(u))du=−∫cos(u)du
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The integral of cosine is sine:
∫cos(u)du=sin(u)
So, the result is: −sin(u)
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The integral of a constant times a function is the constant times the integral of the function:
∫2sin(u)du=2∫sin(u)du
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The integral of sine is negative cosine:
∫sin(u)du=−cos(u)
So, the result is: −2cos(u)
The result is: −ucos(u)+sin(u)−2cos(u)
Now substitute u back in:
xcos(x)−sin(x)−2cos(x)
Method #2
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Rewrite the integrand:
(2−x)sin(x)=−xsin(x)+2sin(x)
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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:
∫(−xsin(x))dx=−∫xsin(x)dx
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Use integration by parts:
∫udv=uv−∫vdu
Let u(x)=x and let dv(x)=sin(x).
Then du(x)=1.
To find v(x):
-
The integral of sine is negative cosine:
∫sin(x)dx=−cos(x)
Now evaluate the sub-integral.
-
The integral of a constant times a function is the constant times the integral of the function:
∫(−cos(x))dx=−∫cos(x)dx
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The integral of cosine is sine:
∫cos(x)dx=sin(x)
So, the result is: −sin(x)
So, the result is: xcos(x)−sin(x)
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The integral of a constant times a function is the constant times the integral of the function:
∫2sin(x)dx=2∫sin(x)dx
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The integral of sine is negative cosine:
∫sin(x)dx=−cos(x)
So, the result is: −2cos(x)
The result is: xcos(x)−sin(x)−2cos(x)
Method #3
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Use integration by parts:
∫udv=uv−∫vdu
Let u(x)=2−x and let dv(x)=sin(x).
Then du(x)=−1.
To find v(x):
-
The integral of sine is negative cosine:
∫sin(x)dx=−cos(x)
Now evaluate the sub-integral.
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The integral of cosine is sine:
∫cos(x)dx=sin(x)
So, the result is: 2xcos(x)−2sin(x)−cos(x)
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Add the constant of integration:
2xcos(x)−2sin(x)−cos(x)+constant
The answer is:
2xcos(x)−2sin(x)−cos(x)+constant
The answer (Indefinite)
[src]
/
|
| (2 - x)*sin(x) sin(x) x*cos(x)
| -------------- dx = C - cos(x) - ------ + --------
| 2 2 2
|
/
∫2(2−x)sin(x)dx=C+2xcos(x)−2sin(x)−cos(x)
The graph
cos(1) sin(1)
1 - ------ - ------
2 2
−2sin(1)−2cos(1)+1
=
cos(1) sin(1)
1 - ------ - ------
2 2
−2sin(1)−2cos(1)+1
Use the examples entering the upper and lower limits of integration.