Integral of (-2x^2-12x+6)cos6x 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:
(−2x2−12x+6)cos(6x)=−2x2cos(6x)−12xcos(6x)+6cos(6x)
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Integrate term-by-term:
-
The integral of a constant times a function is the constant times the integral of the function:
∫(−2x2cos(6x))dx=−2∫x2cos(6x)dx
-
Use integration by parts:
∫udv=uv−∫vdu
Let u(x)=x2 and let dv(x)=cos(6x).
Then du(x)=2x.
To find v(x):
-
Let u=6x.
Then let du=6dx and substitute 6du:
∫36cos(u)du
-
The integral of a constant times a function is the constant times the integral of the function:
∫6cos(u)du=6∫cos(u)du
-
The integral of cosine is sine:
∫cos(u)du=sin(u)
So, the result is: 6sin(u)
Now substitute u back in:
6sin(6x)
Now evaluate the sub-integral.
-
Use integration by parts:
∫udv=uv−∫vdu
Let u(x)=3x and let dv(x)=sin(6x).
Then du(x)=31.
To find v(x):
-
Let u=6x.
Then let du=6dx and substitute 6du:
∫36sin(u)du
-
The integral of a constant times a function is the constant times the integral of the function:
∫6sin(u)du=6∫sin(u)du
-
The integral of sine is negative cosine:
∫sin(u)du=−cos(u)
So, the result is: −6cos(u)
Now substitute u back in:
−6cos(6x)
Now evaluate the sub-integral.
-
The integral of a constant times a function is the constant times the integral of the function:
∫(−18cos(6x))dx=−18∫cos(6x)dx
-
Let u=6x.
Then let du=6dx and substitute 6du:
∫36cos(u)du
-
The integral of a constant times a function is the constant times the integral of the function:
∫6cos(u)du=6∫cos(u)du
-
The integral of cosine is sine:
∫cos(u)du=sin(u)
So, the result is: 6sin(u)
Now substitute u back in:
6sin(6x)
So, the result is: −108sin(6x)
So, the result is: −3x2sin(6x)−9xcos(6x)+54sin(6x)
-
The integral of a constant times a function is the constant times the integral of the function:
∫(−12xcos(6x))dx=−12∫xcos(6x)dx
-
Use integration by parts:
∫udv=uv−∫vdu
Let u(x)=x and let dv(x)=cos(6x).
Then du(x)=1.
To find v(x):
-
Let u=6x.
Then let du=6dx and substitute 6du:
∫36cos(u)du
-
The integral of a constant times a function is the constant times the integral of the function:
∫6cos(u)du=6∫cos(u)du
-
The integral of cosine is sine:
∫cos(u)du=sin(u)
So, the result is: 6sin(u)
Now substitute u back in:
6sin(6x)
Now evaluate the sub-integral.
-
The integral of a constant times a function is the constant times the integral of the function:
∫6sin(6x)dx=6∫sin(6x)dx
-
Let u=6x.
Then let du=6dx and substitute 6du:
∫36sin(u)du
-
The integral of a constant times a function is the constant times the integral of the function:
∫6sin(u)du=6∫sin(u)du
-
The integral of sine is negative cosine:
∫sin(u)du=−cos(u)
So, the result is: −6cos(u)
Now substitute u back in:
−6cos(6x)
So, the result is: −36cos(6x)
So, the result is: −2xsin(6x)−3cos(6x)
-
The integral of a constant times a function is the constant times the integral of the function:
∫6cos(6x)dx=6∫cos(6x)dx
-
Let u=6x.
Then let du=6dx and substitute 6du:
∫36cos(u)du
-
The integral of a constant times a function is the constant times the integral of the function:
∫6cos(u)du=6∫cos(u)du
-
The integral of cosine is sine:
∫cos(u)du=sin(u)
So, the result is: 6sin(u)
Now substitute u back in:
6sin(6x)
So, the result is: sin(6x)
The result is: −3x2sin(6x)−2xsin(6x)−9xcos(6x)+5455sin(6x)−3cos(6x)
Method #2
-
Use integration by parts:
∫udv=uv−∫vdu
Let u(x)=−2x2−12x+6 and let dv(x)=cos(6x).
Then du(x)=−4x−12.
To find v(x):
-
Let u=6x.
Then let du=6dx and substitute 6du:
∫36cos(u)du
-
The integral of a constant times a function is the constant times the integral of the function:
∫6cos(u)du=6∫cos(u)du
-
The integral of cosine is sine:
∫cos(u)du=sin(u)
So, the result is: 6sin(u)
Now substitute u back in:
6sin(6x)
Now evaluate the sub-integral.
-
Use integration by parts:
∫udv=uv−∫vdu
Let u(x)=−32x−2 and let dv(x)=sin(6x).
Then du(x)=−32.
To find v(x):
-
Let u=6x.
Then let du=6dx and substitute 6du:
∫36sin(u)du
-
The integral of a constant times a function is the constant times the integral of the function:
∫6sin(u)du=6∫sin(u)du
-
The integral of sine is negative cosine:
∫sin(u)du=−cos(u)
So, the result is: −6cos(u)
Now substitute u back in:
−6cos(6x)
Now evaluate the sub-integral.
-
The integral of a constant times a function is the constant times the integral of the function:
∫9cos(6x)dx=9∫cos(6x)dx
-
Let u=6x.
Then let du=6dx and substitute 6du:
∫36cos(u)du
-
The integral of a constant times a function is the constant times the integral of the function:
∫6cos(u)du=6∫cos(u)du
-
The integral of cosine is sine:
∫cos(u)du=sin(u)
So, the result is: 6sin(u)
Now substitute u back in:
6sin(6x)
So, the result is: 54sin(6x)
Method #3
-
Rewrite the integrand:
(−2x2−12x+6)cos(6x)=−2x2cos(6x)−12xcos(6x)+6cos(6x)
-
Integrate term-by-term:
-
The integral of a constant times a function is the constant times the integral of the function:
∫(−2x2cos(6x))dx=−2∫x2cos(6x)dx
-
Use integration by parts:
∫udv=uv−∫vdu
Let u(x)=x2 and let dv(x)=cos(6x).
Then du(x)=2x.
To find v(x):
-
Let u=6x.
Then let du=6dx and substitute 6du:
∫36cos(u)du
-
The integral of a constant times a function is the constant times the integral of the function:
∫6cos(u)du=6∫cos(u)du
-
The integral of cosine is sine:
∫cos(u)du=sin(u)
So, the result is: 6sin(u)
Now substitute u back in:
6sin(6x)
Now evaluate the sub-integral.
-
Use integration by parts:
∫udv=uv−∫vdu
Let u(x)=3x and let dv(x)=sin(6x).
Then du(x)=31.
To find v(x):
-
Let u=6x.
Then let du=6dx and substitute 6du:
∫36sin(u)du
-
The integral of a constant times a function is the constant times the integral of the function:
∫6sin(u)du=6∫sin(u)du
-
The integral of sine is negative cosine:
∫sin(u)du=−cos(u)
So, the result is: −6cos(u)
Now substitute u back in:
−6cos(6x)
Now evaluate the sub-integral.
-
The integral of a constant times a function is the constant times the integral of the function:
∫(−18cos(6x))dx=−18∫cos(6x)dx
-
Let u=6x.
Then let du=6dx and substitute 6du:
∫36cos(u)du
-
The integral of a constant times a function is the constant times the integral of the function:
∫6cos(u)du=6∫cos(u)du
-
The integral of cosine is sine:
∫cos(u)du=sin(u)
So, the result is: 6sin(u)
Now substitute u back in:
6sin(6x)
So, the result is: −108sin(6x)
So, the result is: −3x2sin(6x)−9xcos(6x)+54sin(6x)
-
The integral of a constant times a function is the constant times the integral of the function:
∫(−12xcos(6x))dx=−12∫xcos(6x)dx
-
Use integration by parts:
∫udv=uv−∫vdu
Let u(x)=x and let dv(x)=cos(6x).
Then du(x)=1.
To find v(x):
-
Let u=6x.
Then let du=6dx and substitute 6du:
∫36cos(u)du
-
The integral of a constant times a function is the constant times the integral of the function:
∫6cos(u)du=6∫cos(u)du
-
The integral of cosine is sine:
∫cos(u)du=sin(u)
So, the result is: 6sin(u)
Now substitute u back in:
6sin(6x)
Now evaluate the sub-integral.
-
The integral of a constant times a function is the constant times the integral of the function:
∫6sin(6x)dx=6∫sin(6x)dx
-
Let u=6x.
Then let du=6dx and substitute 6du:
∫36sin(u)du
-
The integral of a constant times a function is the constant times the integral of the function:
∫6sin(u)du=6∫sin(u)du
-
The integral of sine is negative cosine:
∫sin(u)du=−cos(u)
So, the result is: −6cos(u)
Now substitute u back in:
−6cos(6x)
So, the result is: −36cos(6x)
So, the result is: −2xsin(6x)−3cos(6x)
-
The integral of a constant times a function is the constant times the integral of the function:
∫6cos(6x)dx=6∫cos(6x)dx
-
Let u=6x.
Then let du=6dx and substitute 6du:
∫36cos(u)du
-
The integral of a constant times a function is the constant times the integral of the function:
∫6cos(u)du=6∫cos(u)du
-
The integral of cosine is sine:
∫cos(u)du=sin(u)
So, the result is: 6sin(u)
Now substitute u back in:
6sin(6x)
So, the result is: sin(6x)
The result is: −3x2sin(6x)−2xsin(6x)−9xcos(6x)+5455sin(6x)−3cos(6x)
-
Add the constant of integration:
−3x2sin(6x)−2xsin(6x)−9xcos(6x)+5455sin(6x)−3cos(6x)+constant
The answer is:
−3x2sin(6x)−2xsin(6x)−9xcos(6x)+5455sin(6x)−3cos(6x)+constant
The answer (Indefinite)
[src]
/
| 2
| / 2 \ cos(6*x) 55*sin(6*x) x *sin(6*x) x*cos(6*x)
| \- 2*x - 12*x + 6/*cos(6*x) dx = C - -------- + ----------- - 2*x*sin(6*x) - ----------- - ----------
| 3 54 3 9
/
6−18(36x2−2)sin(6x)+12xcos(6x)−2(6xsin(6x)+cos(6x))+6sin(6x)
The graph
1 71*sin(6) 4*cos(6)
- - --------- - --------
3 54 9
31−5471sin6+24cos6
=
1 71*sin(6) 4*cos(6)
- - --------- - --------
3 54 9
−94cos(6)+31−5471sin(6)
Use the examples entering the upper and lower limits of integration.