Integral of (4x-2)^2cos3x 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:
(4x−2)2cos(3x)=16x2cos(3x)−16xcos(3x)+4cos(3x)
-
Integrate term-by-term:
-
The integral of a constant times a function is the constant times the integral of the function:
∫16x2cos(3x)dx=16∫x2cos(3x)dx
-
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)
So, the result is: 316x2sin(3x)+932xcos(3x)−2732sin(3x)
-
The integral of a constant times a function is the constant times the integral of the function:
∫(−16xcos(3x))dx=−16∫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: −316xsin(3x)−916cos(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: 316x2sin(3x)−316xsin(3x)+932xcos(3x)+274sin(3x)−916cos(3x)
Method #2
-
Use integration by parts:
∫udv=uv−∫vdu
Let u(x)=16x2−16x+4 and let dv(x)=cos(3x).
Then du(x)=32x−16.
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)=332x−316 and let dv(x)=sin(3x).
Then du(x)=332.
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:
∫(−932cos(3x))dx=−932∫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: −2732sin(3x)
Method #3
-
Rewrite the integrand:
(4x−2)2cos(3x)=16x2cos(3x)−16xcos(3x)+4cos(3x)
-
Integrate term-by-term:
-
The integral of a constant times a function is the constant times the integral of the function:
∫16x2cos(3x)dx=16∫x2cos(3x)dx
-
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)
So, the result is: 316x2sin(3x)+932xcos(3x)−2732sin(3x)
-
The integral of a constant times a function is the constant times the integral of the function:
∫(−16xcos(3x))dx=−16∫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: −316xsin(3x)−916cos(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: 316x2sin(3x)−316xsin(3x)+932xcos(3x)+274sin(3x)−916cos(3x)
-
Add the constant of integration:
316x2sin(3x)−316xsin(3x)+932xcos(3x)+274sin(3x)−916cos(3x)+constant
The answer is:
316x2sin(3x)−316xsin(3x)+932xcos(3x)+274sin(3x)−916cos(3x)+constant
The answer (Indefinite)
[src]
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| 2
| 2 16*cos(3*x) 4*sin(3*x) 16*x*sin(3*x) 16*x *sin(3*x) 32*x*cos(3*x)
| (4*x - 2) *cos(3*x) dx = C - ----------- + ---------- - ------------- + -------------- + -------------
| 9 27 3 3 9
/
3916((9x2−2)sin(3x)+6xcos(3x))−316(3xsin(3x)+cos(3x))+4sin(3x)
The graph
16 16*cos(3) 292*sin(3)
- -- + --------- + ----------
9 3 27
27292sin3+144cos3−916
=
16 16*cos(3) 292*sin(3)
- -- + --------- + ----------
9 3 27
316cos(3)−916+27292sin(3)
Use the examples entering the upper and lower limits of integration.