Integral of (x+2)^2*cos(3x) dx
The solution
Detail solution
-
There are multiple ways to do this integral.
Method #1
-
Rewrite the integrand:
(x+2)2cos(3x)=x2cos(3x)+4xcos(3x)+4cos(3x)
-
Integrate term-by-term:
-
Use integration by parts:
∫udv=uv−∫vdu
Let u(x)=x2 and let dv(x)=cos(3x).
Then du(x)=2x.
To find v(x):
-
Let u=3x.
Then let du=3dx and substitute 3du:
∫9cos(u)du
-
The integral of a constant times a function is the constant times the integral of the function:
∫3cos(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.
-
Use integration by parts:
∫udv=uv−∫vdu
Let u(x)=32x and let dv(x)=sin(3x).
Then du(x)=32.
To find v(x):
-
Let u=3x.
Then let du=3dx and substitute 3du:
∫9sin(u)du
-
The integral of a constant times a function is the constant times the integral of the function:
∫3sin(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:
∫(−92cos(3x))dx=−92∫cos(3x)dx
-
Let u=3x.
Then let du=3dx and substitute 3du:
∫9cos(u)du
-
The integral of a constant times a function is the constant times the integral of the function:
∫3cos(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: −272sin(3x)
-
The integral of a constant times a function is the constant times the integral of the function:
∫4xcos(3x)dx=4∫xcos(3x)dx
-
Use integration by parts:
∫udv=uv−∫vdu
Let u(x)=x and let dv(x)=cos(3x).
Then du(x)=1.
To find v(x):
-
Let u=3x.
Then let du=3dx and substitute 3du:
∫9cos(u)du
-
The integral of a constant times a function is the constant times the integral of the function:
∫3cos(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:
∫3sin(3x)dx=3∫sin(3x)dx
-
Let u=3x.
Then let du=3dx and substitute 3du:
∫9sin(u)du
-
The integral of a constant times a function is the constant times the integral of the function:
∫3sin(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: −9cos(3x)
So, the result is: 34xsin(3x)+94cos(3x)
-
The integral of a constant times a function is the constant times the integral of the function:
∫4cos(3x)dx=4∫cos(3x)dx
-
Let u=3x.
Then let du=3dx and substitute 3du:
∫9cos(u)du
-
The integral of a constant times a function is the constant times the integral of the function:
∫3cos(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: 34sin(3x)
The result is: 3x2sin(3x)+34xsin(3x)+92xcos(3x)+2734sin(3x)+94cos(3x)
Method #2
-
Use integration by parts:
∫udv=uv−∫vdu
Let u(x)=x2+4x+4 and let dv(x)=cos(3x).
Then du(x)=2x+4.
To find v(x):
-
Let u=3x.
Then let du=3dx and substitute 3du:
∫9cos(u)du
-
The integral of a constant times a function is the constant times the integral of the function:
∫3cos(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.
-
Use integration by parts:
∫udv=uv−∫vdu
Let u(x)=32x+34 and let dv(x)=sin(3x).
Then du(x)=32.
To find v(x):
-
Let u=3x.
Then let du=3dx and substitute 3du:
∫9sin(u)du
-
The integral of a constant times a function is the constant times the integral of the function:
∫3sin(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:
∫(−92cos(3x))dx=−92∫cos(3x)dx
-
Let u=3x.
Then let du=3dx and substitute 3du:
∫9cos(u)du
-
The integral of a constant times a function is the constant times the integral of the function:
∫3cos(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: −272sin(3x)
Method #3
-
Rewrite the integrand:
(x+2)2cos(3x)=x2cos(3x)+4xcos(3x)+4cos(3x)
-
Integrate term-by-term:
-
Use integration by parts:
∫udv=uv−∫vdu
Let u(x)=x2 and let dv(x)=cos(3x).
Then du(x)=2x.
To find v(x):
-
Let u=3x.
Then let du=3dx and substitute 3du:
∫9cos(u)du
-
The integral of a constant times a function is the constant times the integral of the function:
∫3cos(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.
-
Use integration by parts:
∫udv=uv−∫vdu
Let u(x)=32x and let dv(x)=sin(3x).
Then du(x)=32.
To find v(x):
-
Let u=3x.
Then let du=3dx and substitute 3du:
∫9sin(u)du
-
The integral of a constant times a function is the constant times the integral of the function:
∫3sin(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:
∫(−92cos(3x))dx=−92∫cos(3x)dx
-
Let u=3x.
Then let du=3dx and substitute 3du:
∫9cos(u)du
-
The integral of a constant times a function is the constant times the integral of the function:
∫3cos(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: −272sin(3x)
-
The integral of a constant times a function is the constant times the integral of the function:
∫4xcos(3x)dx=4∫xcos(3x)dx
-
Use integration by parts:
∫udv=uv−∫vdu
Let u(x)=x and let dv(x)=cos(3x).
Then du(x)=1.
To find v(x):
-
Let u=3x.
Then let du=3dx and substitute 3du:
∫9cos(u)du
-
The integral of a constant times a function is the constant times the integral of the function:
∫3cos(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:
∫3sin(3x)dx=3∫sin(3x)dx
-
Let u=3x.
Then let du=3dx and substitute 3du:
∫9sin(u)du
-
The integral of a constant times a function is the constant times the integral of the function:
∫3sin(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: −9cos(3x)
So, the result is: 34xsin(3x)+94cos(3x)
-
The integral of a constant times a function is the constant times the integral of the function:
∫4cos(3x)dx=4∫cos(3x)dx
-
Let u=3x.
Then let du=3dx and substitute 3du:
∫9cos(u)du
-
The integral of a constant times a function is the constant times the integral of the function:
∫3cos(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: 34sin(3x)
The result is: 3x2sin(3x)+34xsin(3x)+92xcos(3x)+2734sin(3x)+94cos(3x)
-
Add the constant of integration:
3x2sin(3x)+34xsin(3x)+92xcos(3x)+2734sin(3x)+94cos(3x)+constant
The answer is:
3x2sin(3x)+34xsin(3x)+92xcos(3x)+2734sin(3x)+94cos(3x)+constant
The answer (Indefinite)
[src]
/
| 2
| 2 4*cos(3*x) 34*sin(3*x) x *sin(3*x) 2*x*cos(3*x) 4*x*sin(3*x)
| (x + 2) *cos(3*x) dx = C + ---------- + ----------- + ----------- + ------------ + ------------
| 9 27 3 9 3
/
39(9x2−2)sin(3x)+6xcos(3x)+34(3xsin(3x)+cos(3x))+4sin(3x)
The graph
4 2*sin(6)
- - --------
9 27
94−272sin6
=
4 2*sin(6)
- - --------
9 27
−272sin(6)+94
Use the examples entering the upper and lower limits of integration.