Integral of (x^2+4x-2)sin3xdx dx
The solution
Detail solution
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There are multiple ways to do this integral.
Method #1
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Rewrite the integrand:
((x2+4x)−2)sin(3x)=x2sin(3x)+4xsin(3x)−2sin(3x)
-
Integrate term-by-term:
-
Use integration by parts:
∫udv=uv−∫vdu
Let u(x)=x2 and let dv(x)=sin(3x).
Then du(x)=2x.
To find v(x):
-
Let u=3x.
Then let du=3dx and substitute 3du:
∫3sin(u)du
-
The integral of a constant times a function is the constant times the integral of the function:
∫sin(u)du=3∫sin(u)du
-
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)
Now evaluate the sub-integral.
-
Use integration by parts:
∫udv=uv−∫vdu
Let u(x)=−32x and let dv(x)=cos(3x).
Then du(x)=−32.
To find v(x):
-
Let u=3x.
Then let du=3dx and substitute 3du:
∫3cos(u)du
-
The integral of a constant times a function is the constant times the integral of the function:
∫cos(u)du=3∫cos(u)du
-
The integral of cosine is sine:
∫cos(u)du=sin(u)
So, the result is: 3sin(u)
Now substitute u back in:
3sin(3x)
Now evaluate the sub-integral.
-
The integral of a constant times a function is the constant times the integral of the function:
∫(−92sin(3x))dx=−92∫sin(3x)dx
-
Let u=3x.
Then let du=3dx and substitute 3du:
∫3sin(u)du
-
The integral of a constant times a function is the constant times the integral of the function:
∫sin(u)du=3∫sin(u)du
-
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)
So, the result is: 272cos(3x)
-
The integral of a constant times a function is the constant times the integral of the function:
∫4xsin(3x)dx=4∫xsin(3x)dx
-
Use integration by parts:
∫udv=uv−∫vdu
Let u(x)=x and let dv(x)=sin(3x).
Then du(x)=1.
To find v(x):
-
Let u=3x.
Then let du=3dx and substitute 3du:
∫3sin(u)du
-
The integral of a constant times a function is the constant times the integral of the function:
∫sin(u)du=3∫sin(u)du
-
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)
Now evaluate the sub-integral.
-
The integral of a constant times a function is the constant times the integral of the function:
∫(−3cos(3x))dx=−3∫cos(3x)dx
-
Let u=3x.
Then let du=3dx and substitute 3du:
∫3cos(u)du
-
The integral of a constant times a function is the constant times the integral of the function:
∫cos(u)du=3∫cos(u)du
-
The integral of cosine is sine:
∫cos(u)du=sin(u)
So, the result is: 3sin(u)
Now substitute u back in:
3sin(3x)
So, the result is: −9sin(3x)
So, the result is: −34xcos(3x)+94sin(3x)
-
The integral of a constant times a function is the constant times the integral of the function:
∫(−2sin(3x))dx=−2∫sin(3x)dx
-
Let u=3x.
Then let du=3dx and substitute 3du:
∫3sin(u)du
-
The integral of a constant times a function is the constant times the integral of the function:
∫sin(u)du=3∫sin(u)du
-
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)
So, the result is: 32cos(3x)
The result is: −3x2cos(3x)+92xsin(3x)−34xcos(3x)+94sin(3x)+2720cos(3x)
Method #2
-
Use integration by parts:
∫udv=uv−∫vdu
Let u(x)=x2+4x−2 and let dv(x)=sin(3x).
Then du(x)=2x+4.
To find v(x):
-
Let u=3x.
Then let du=3dx and substitute 3du:
∫3sin(u)du
-
The integral of a constant times a function is the constant times the integral of the function:
∫sin(u)du=3∫sin(u)du
-
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)
Now evaluate the sub-integral.
-
Use integration by parts:
∫udv=uv−∫vdu
Let u(x)=−32x−34 and let dv(x)=cos(3x).
Then du(x)=−32.
To find v(x):
-
Let u=3x.
Then let du=3dx and substitute 3du:
∫3cos(u)du
-
The integral of a constant times a function is the constant times the integral of the function:
∫cos(u)du=3∫cos(u)du
-
The integral of cosine is sine:
∫cos(u)du=sin(u)
So, the result is: 3sin(u)
Now substitute u back in:
3sin(3x)
Now evaluate the sub-integral.
-
The integral of a constant times a function is the constant times the integral of the function:
∫(−92sin(3x))dx=−92∫sin(3x)dx
-
Let u=3x.
Then let du=3dx and substitute 3du:
∫3sin(u)du
-
The integral of a constant times a function is the constant times the integral of the function:
∫sin(u)du=3∫sin(u)du
-
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)
So, the result is: 272cos(3x)
Method #3
-
Rewrite the integrand:
((x2+4x)−2)sin(3x)=x2sin(3x)+4xsin(3x)−2sin(3x)
-
Integrate term-by-term:
-
Use integration by parts:
∫udv=uv−∫vdu
Let u(x)=x2 and let dv(x)=sin(3x).
Then du(x)=2x.
To find v(x):
-
Let u=3x.
Then let du=3dx and substitute 3du:
∫3sin(u)du
-
The integral of a constant times a function is the constant times the integral of the function:
∫sin(u)du=3∫sin(u)du
-
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)
Now evaluate the sub-integral.
-
Use integration by parts:
∫udv=uv−∫vdu
Let u(x)=−32x and let dv(x)=cos(3x).
Then du(x)=−32.
To find v(x):
-
Let u=3x.
Then let du=3dx and substitute 3du:
∫3cos(u)du
-
The integral of a constant times a function is the constant times the integral of the function:
∫cos(u)du=3∫cos(u)du
-
The integral of cosine is sine:
∫cos(u)du=sin(u)
So, the result is: 3sin(u)
Now substitute u back in:
3sin(3x)
Now evaluate the sub-integral.
-
The integral of a constant times a function is the constant times the integral of the function:
∫(−92sin(3x))dx=−92∫sin(3x)dx
-
Let u=3x.
Then let du=3dx and substitute 3du:
∫3sin(u)du
-
The integral of a constant times a function is the constant times the integral of the function:
∫sin(u)du=3∫sin(u)du
-
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)
So, the result is: 272cos(3x)
-
The integral of a constant times a function is the constant times the integral of the function:
∫4xsin(3x)dx=4∫xsin(3x)dx
-
Use integration by parts:
∫udv=uv−∫vdu
Let u(x)=x and let dv(x)=sin(3x).
Then du(x)=1.
To find v(x):
-
Let u=3x.
Then let du=3dx and substitute 3du:
∫3sin(u)du
-
The integral of a constant times a function is the constant times the integral of the function:
∫sin(u)du=3∫sin(u)du
-
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)
Now evaluate the sub-integral.
-
The integral of a constant times a function is the constant times the integral of the function:
∫(−3cos(3x))dx=−3∫cos(3x)dx
-
Let u=3x.
Then let du=3dx and substitute 3du:
∫3cos(u)du
-
The integral of a constant times a function is the constant times the integral of the function:
∫cos(u)du=3∫cos(u)du
-
The integral of cosine is sine:
∫cos(u)du=sin(u)
So, the result is: 3sin(u)
Now substitute u back in:
3sin(3x)
So, the result is: −9sin(3x)
So, the result is: −34xcos(3x)+94sin(3x)
-
The integral of a constant times a function is the constant times the integral of the function:
∫(−2sin(3x))dx=−2∫sin(3x)dx
-
Let u=3x.
Then let du=3dx and substitute 3du:
∫3sin(u)du
-
The integral of a constant times a function is the constant times the integral of the function:
∫sin(u)du=3∫sin(u)du
-
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)
So, the result is: 32cos(3x)
The result is: −3x2cos(3x)+92xsin(3x)−34xcos(3x)+94sin(3x)+2720cos(3x)
-
Add the constant of integration:
−3x2cos(3x)+92xsin(3x)−34xcos(3x)+94sin(3x)+2720cos(3x)+constant
The answer is:
−3x2cos(3x)+92xsin(3x)−34xcos(3x)+94sin(3x)+2720cos(3x)+constant
The answer (Indefinite)
[src]
/
| 2
| / 2 \ 4*sin(3*x) 20*cos(3*x) 4*x*cos(3*x) x *cos(3*x) 2*x*sin(3*x)
| \x + 4*x - 2/*sin(3*x) dx = C + ---------- + ----------- - ------------ - ----------- + ------------
| 9 27 3 3 9
/
∫((x2+4x)−2)sin(3x)dx=C−3x2cos(3x)+92xsin(3x)−34xcos(3x)+94sin(3x)+2720cos(3x)
The graph
20 25*cos(3) 2*sin(3)
- -- - --------- + --------
27 27 3
−2720+32sin(3)−2725cos(3)
=
20 25*cos(3) 2*sin(3)
- -- - --------- + --------
27 27 3
−2720+32sin(3)−2725cos(3)
-20/27 - 25*cos(3)/27 + 2*sin(3)/3
Use the examples entering the upper and lower limits of integration.