Integral of cos^5(2x) dx
The solution
Detail solution
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Rewrite the integrand:
cos5(2x)=(1−sin2(2x))2cos(2x)
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There are multiple ways to do this integral.
Method #1
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Let u=2x.
Then let du=2dx and substitute du:
∫(2sin4(u)cos(u)−sin2(u)cos(u)+2cos(u))du
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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:
∫2sin4(u)cos(u)du=2∫sin4(u)cos(u)du
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Let u=sin(u).
Then let du=cos(u)du and substitute du:
∫u4du
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The integral of un is n+1un+1 when n=−1:
∫u4du=5u5
Now substitute u back in:
5sin5(u)
So, the result is: 10sin5(u)
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The integral of a constant times a function is the constant times the integral of the function:
∫(−sin2(u)cos(u))du=−∫sin2(u)cos(u)du
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Let u=sin(u).
Then let du=cos(u)du and substitute du:
∫u2du
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The integral of un is n+1un+1 when n=−1:
∫u2du=3u3
Now substitute u back in:
3sin3(u)
So, the result is: −3sin3(u)
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The integral of a constant times a function is the constant times the integral of the function:
∫2cos(u)du=2∫cos(u)du
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The integral of cosine is sine:
∫cos(u)du=sin(u)
So, the result is: 2sin(u)
The result is: 10sin5(u)−3sin3(u)+2sin(u)
Now substitute u back in:
10sin5(2x)−3sin3(2x)+2sin(2x)
Method #2
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Rewrite the integrand:
(1−sin2(2x))2cos(2x)=sin4(2x)cos(2x)−2sin2(2x)cos(2x)+cos(2x)
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Integrate term-by-term:
-
Let u=sin(2x).
Then let du=2cos(2x)dx and substitute 2du:
∫4u4du
-
The integral of a constant times a function is the constant times the integral of the function:
∫2u4du=2∫u4du
-
The integral of un is n+1un+1 when n=−1:
∫u4du=5u5
So, the result is: 10u5
Now substitute u back in:
10sin5(2x)
-
The integral of a constant times a function is the constant times the integral of the function:
∫(−2sin2(2x)cos(2x))dx=−2∫sin2(2x)cos(2x)dx
-
Let u=sin(2x).
Then let du=2cos(2x)dx and substitute 2du:
∫4u2du
-
The integral of a constant times a function is the constant times the integral of the function:
∫2u2du=2∫u2du
-
The integral of un is n+1un+1 when n=−1:
∫u2du=3u3
So, the result is: 6u3
Now substitute u back in:
6sin3(2x)
So, the result is: −3sin3(2x)
-
Let u=2x.
Then let du=2dx and substitute 2du:
∫4cos(u)du
-
The integral of a constant times a function is the constant times the integral of the function:
∫2cos(u)du=2∫cos(u)du
-
The integral of cosine is sine:
∫cos(u)du=sin(u)
So, the result is: 2sin(u)
Now substitute u back in:
2sin(2x)
The result is: 10sin5(2x)−3sin3(2x)+2sin(2x)
Method #3
-
Rewrite the integrand:
(1−sin2(2x))2cos(2x)=sin4(2x)cos(2x)−2sin2(2x)cos(2x)+cos(2x)
-
Integrate term-by-term:
-
Let u=sin(2x).
Then let du=2cos(2x)dx and substitute 2du:
∫4u4du
-
The integral of a constant times a function is the constant times the integral of the function:
∫2u4du=2∫u4du
-
The integral of un is n+1un+1 when n=−1:
∫u4du=5u5
So, the result is: 10u5
Now substitute u back in:
10sin5(2x)
-
The integral of a constant times a function is the constant times the integral of the function:
∫(−2sin2(2x)cos(2x))dx=−2∫sin2(2x)cos(2x)dx
-
Let u=sin(2x).
Then let du=2cos(2x)dx and substitute 2du:
∫4u2du
-
The integral of a constant times a function is the constant times the integral of the function:
∫2u2du=2∫u2du
-
The integral of un is n+1un+1 when n=−1:
∫u2du=3u3
So, the result is: 6u3
Now substitute u back in:
6sin3(2x)
So, the result is: −3sin3(2x)
-
Let u=2x.
Then let du=2dx and substitute 2du:
∫4cos(u)du
-
The integral of a constant times a function is the constant times the integral of the function:
∫2cos(u)du=2∫cos(u)du
-
The integral of cosine is sine:
∫cos(u)du=sin(u)
So, the result is: 2sin(u)
Now substitute u back in:
2sin(2x)
The result is: 10sin5(2x)−3sin3(2x)+2sin(2x)
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Add the constant of integration:
10sin5(2x)−3sin3(2x)+2sin(2x)+constant
The answer is:
10sin5(2x)−3sin3(2x)+2sin(2x)+constant
The answer (Indefinite)
[src]
/
| 3 5
| 5 sin(2*x) sin (2*x) sin (2*x)
| cos (2*x) dx = C + -------- - --------- + ---------
| 2 3 10
/
25sin5(2x)−32sin3(2x)+sin(2x)
The graph
3 5
sin(2) sin (2) sin (2)
------ - ------- + -------
2 3 10
303sin52−10sin32+15sin2
=
3 5
sin(2) sin (2) sin (2)
------ - ------- + -------
2 3 10
−3sin3(2)+10sin5(2)+2sin(2)
Use the examples entering the upper and lower limits of integration.