Integral of sin8x*cos3x dx
The solution
Detail solution
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Rewrite the integrand:
sin(8x)cos(3x)=−512sin7(x)cos4(x)+384sin7(x)cos2(x)+768sin5(x)cos4(x)−576sin5(x)cos2(x)−320sin3(x)cos4(x)+240sin3(x)cos2(x)+32sin(x)cos4(x)−24sin(x)cos2(x)
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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:
∫(−512sin7(x)cos4(x))dx=−512∫sin7(x)cos4(x)dx
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Rewrite the integrand:
sin7(x)cos4(x)=(1−cos2(x))3sin(x)cos4(x)
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There are multiple ways to do this integral.
Method #1
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Let u=cos(x).
Then let du=−sin(x)dx and substitute du:
∫(u10−3u8+3u6−u4)du
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Integrate term-by-term:
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The integral of un is n+1un+1 when n=−1:
∫u10du=11u11
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The integral of a constant times a function is the constant times the integral of the function:
∫(−3u8)du=−3∫u8du
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The integral of un is n+1un+1 when n=−1:
∫u8du=9u9
So, the result is: −3u9
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The integral of a constant times a function is the constant times the integral of the function:
∫3u6du=3∫u6du
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The integral of un is n+1un+1 when n=−1:
∫u6du=7u7
So, the result is: 73u7
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The integral of a constant times a function is the constant times the integral of the function:
∫(−u4)du=−∫u4du
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The integral of un is n+1un+1 when n=−1:
∫u4du=5u5
So, the result is: −5u5
The result is: 11u11−3u9+73u7−5u5
Now substitute u back in:
11cos11(x)−3cos9(x)+73cos7(x)−5cos5(x)
Method #2
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Rewrite the integrand:
(1−cos2(x))3sin(x)cos4(x)=−sin(x)cos10(x)+3sin(x)cos8(x)−3sin(x)cos6(x)+sin(x)cos4(x)
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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:
∫(−sin(x)cos10(x))dx=−∫sin(x)cos10(x)dx
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Let u=cos(x).
Then let du=−sin(x)dx and substitute −du:
∫u10du
-
The integral of a constant times a function is the constant times the integral of the function:
∫(−u10)du=−∫u10du
-
The integral of un is n+1un+1 when n=−1:
∫u10du=11u11
So, the result is: −11u11
Now substitute u back in:
−11cos11(x)
So, the result is: 11cos11(x)
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The integral of a constant times a function is the constant times the integral of the function:
∫3sin(x)cos8(x)dx=3∫sin(x)cos8(x)dx
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Let u=cos(x).
Then let du=−sin(x)dx and substitute −du:
∫u8du
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The integral of a constant times a function is the constant times the integral of the function:
∫(−u8)du=−∫u8du
-
The integral of un is n+1un+1 when n=−1:
∫u8du=9u9
So, the result is: −9u9
Now substitute u back in:
−9cos9(x)
So, the result is: −3cos9(x)
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The integral of a constant times a function is the constant times the integral of the function:
∫(−3sin(x)cos6(x))dx=−3∫sin(x)cos6(x)dx
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Let u=cos(x).
Then let du=−sin(x)dx and substitute −du:
∫u6du
-
The integral of a constant times a function is the constant times the integral of the function:
∫(−u6)du=−∫u6du
-
The integral of un is n+1un+1 when n=−1:
∫u6du=7u7
So, the result is: −7u7
Now substitute u back in:
−7cos7(x)
So, the result is: 73cos7(x)
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Let u=cos(x).
Then let du=−sin(x)dx and substitute −du:
∫u4du
-
The integral of a constant times a function is the constant times the integral of the function:
∫(−u4)du=−∫u4du
-
The integral of un is n+1un+1 when n=−1:
∫u4du=5u5
So, the result is: −5u5
Now substitute u back in:
−5cos5(x)
The result is: 11cos11(x)−3cos9(x)+73cos7(x)−5cos5(x)
Method #3
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Rewrite the integrand:
(1−cos2(x))3sin(x)cos4(x)=−sin(x)cos10(x)+3sin(x)cos8(x)−3sin(x)cos6(x)+sin(x)cos4(x)
-
Integrate term-by-term:
-
The integral of a constant times a function is the constant times the integral of the function:
∫(−sin(x)cos10(x))dx=−∫sin(x)cos10(x)dx
-
Let u=cos(x).
Then let du=−sin(x)dx and substitute −du:
∫u10du
-
The integral of a constant times a function is the constant times the integral of the function:
∫(−u10)du=−∫u10du
-
The integral of un is n+1un+1 when n=−1:
∫u10du=11u11
So, the result is: −11u11
Now substitute u back in:
−11cos11(x)
So, the result is: 11cos11(x)
-
The integral of a constant times a function is the constant times the integral of the function:
∫3sin(x)cos8(x)dx=3∫sin(x)cos8(x)dx
-
Let u=cos(x).
Then let du=−sin(x)dx and substitute −du:
∫u8du
-
The integral of a constant times a function is the constant times the integral of the function:
∫(−u8)du=−∫u8du
-
The integral of un is n+1un+1 when n=−1:
∫u8du=9u9
So, the result is: −9u9
Now substitute u back in:
−9cos9(x)
So, the result is: −3cos9(x)
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The integral of a constant times a function is the constant times the integral of the function:
∫(−3sin(x)cos6(x))dx=−3∫sin(x)cos6(x)dx
-
Let u=cos(x).
Then let du=−sin(x)dx and substitute −du:
∫u6du
-
The integral of a constant times a function is the constant times the integral of the function:
∫(−u6)du=−∫u6du
-
The integral of un is n+1un+1 when n=−1:
∫u6du=7u7
So, the result is: −7u7
Now substitute u back in:
−7cos7(x)
So, the result is: 73cos7(x)
-
Let u=cos(x).
Then let du=−sin(x)dx and substitute −du:
∫u4du
-
The integral of a constant times a function is the constant times the integral of the function:
∫(−u4)du=−∫u4du
-
The integral of un is n+1un+1 when n=−1:
∫u4du=5u5
So, the result is: −5u5
Now substitute u back in:
−5cos5(x)
The result is: 11cos11(x)−3cos9(x)+73cos7(x)−5cos5(x)
So, the result is: −11512cos11(x)+3512cos9(x)−71536cos7(x)+5512cos5(x)
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The integral of a constant times a function is the constant times the integral of the function:
∫384sin7(x)cos2(x)dx=384∫sin7(x)cos2(x)dx
-
Rewrite the integrand:
sin7(x)cos2(x)=(1−cos2(x))3sin(x)cos2(x)
-
Let u=cos(x).
Then let du=−sin(x)dx and substitute du:
∫(u8−3u6+3u4−u2)du
-
Integrate term-by-term:
-
The integral of un is n+1un+1 when n=−1:
∫u8du=9u9
-
The integral of a constant times a function is the constant times the integral of the function:
∫(−3u6)du=−3∫u6du
-
The integral of un is n+1un+1 when n=−1:
∫u6du=7u7
So, the result is: −73u7
-
The integral of a constant times a function is the constant times the integral of the function:
∫3u4du=3∫u4du
-
The integral of un is n+1un+1 when n=−1:
∫u4du=5u5
So, the result is: 53u5
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The integral of a constant times a function is the constant times the integral of the function:
∫(−u2)du=−∫u2du
-
The integral of un is n+1un+1 when n=−1:
∫u2du=3u3
So, the result is: −3u3
The result is: 9u9−73u7+53u5−3u3
Now substitute u back in:
9cos9(x)−73cos7(x)+53cos5(x)−3cos3(x)
So, the result is: 3128cos9(x)−71152cos7(x)+51152cos5(x)−128cos3(x)
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The integral of a constant times a function is the constant times the integral of the function:
∫768sin5(x)cos4(x)dx=768∫sin5(x)cos4(x)dx
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Rewrite the integrand:
sin5(x)cos4(x)=(1−cos2(x))2sin(x)cos4(x)
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Let u=cos(x).
Then let du=−sin(x)dx and substitute du:
∫(−u8+2u6−u4)du
-
Integrate term-by-term:
-
The integral of a constant times a function is the constant times the integral of the function:
∫(−u8)du=−∫u8du
-
The integral of un is n+1un+1 when n=−1:
∫u8du=9u9
So, the result is: −9u9
-
The integral of a constant times a function is the constant times the integral of the function:
∫2u6du=2∫u6du
-
The integral of un is n+1un+1 when n=−1:
∫u6du=7u7
So, the result is: 72u7
-
The integral of a constant times a function is the constant times the integral of the function:
∫(−u4)du=−∫u4du
-
The integral of un is n+1un+1 when n=−1:
∫u4du=5u5
So, the result is: −5u5
The result is: −9u9+72u7−5u5
Now substitute u back in:
−9cos9(x)+72cos7(x)−5cos5(x)
So, the result is: −3256cos9(x)+71536cos7(x)−5768cos5(x)
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The integral of a constant times a function is the constant times the integral of the function:
∫(−576sin5(x)cos2(x))dx=−576∫sin5(x)cos2(x)dx
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Rewrite the integrand:
sin5(x)cos2(x)=(1−cos2(x))2sin(x)cos2(x)
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Let u=cos(x).
Then let du=−sin(x)dx and substitute du:
∫(−u6+2u4−u2)du
-
Integrate term-by-term:
-
The integral of a constant times a function is the constant times the integral of the function:
∫(−u6)du=−∫u6du
-
The integral of un is n+1un+1 when n=−1:
∫u6du=7u7
So, the result is: −7u7
-
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: 52u5
-
The integral of a constant times a function is the constant times the integral of the function:
∫(−u2)du=−∫u2du
-
The integral of un is n+1un+1 when n=−1:
∫u2du=3u3
So, the result is: −3u3
The result is: −7u7+52u5−3u3
Now substitute u back in:
−7cos7(x)+52cos5(x)−3cos3(x)
So, the result is: 7576cos7(x)−51152cos5(x)+192cos3(x)
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The integral of a constant times a function is the constant times the integral of the function:
∫(−320sin3(x)cos4(x))dx=−320∫sin3(x)cos4(x)dx
-
Rewrite the integrand:
sin3(x)cos4(x)=(1−cos2(x))sin(x)cos4(x)
-
Let u=cos(x).
Then let du=−sin(x)dx and substitute du:
∫(u6−u4)du
-
Integrate term-by-term:
-
The integral of un is n+1un+1 when n=−1:
∫u6du=7u7
-
The integral of a constant times a function is the constant times the integral of the function:
∫(−u4)du=−∫u4du
-
The integral of un is n+1un+1 when n=−1:
∫u4du=5u5
So, the result is: −5u5
The result is: 7u7−5u5
Now substitute u back in:
7cos7(x)−5cos5(x)
So, the result is: −7320cos7(x)+64cos5(x)
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The integral of a constant times a function is the constant times the integral of the function:
∫240sin3(x)cos2(x)dx=240∫sin3(x)cos2(x)dx
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Rewrite the integrand:
sin3(x)cos2(x)=(1−cos2(x))sin(x)cos2(x)
-
Let u=cos(x).
Then let du=−sin(x)dx and substitute du:
∫(u4−u2)du
-
Integrate term-by-term:
-
The integral of un is n+1un+1 when n=−1:
∫u4du=5u5
-
The integral of a constant times a function is the constant times the integral of the function:
∫(−u2)du=−∫u2du
-
The integral of un is n+1un+1 when n=−1:
∫u2du=3u3
So, the result is: −3u3
The result is: 5u5−3u3
Now substitute u back in:
5cos5(x)−3cos3(x)
So, the result is: 48cos5(x)−80cos3(x)
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The integral of a constant times a function is the constant times the integral of the function:
∫32sin(x)cos4(x)dx=32∫sin(x)cos4(x)dx
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Let u=cos(x).
Then let du=−sin(x)dx and substitute −du:
∫u4du
-
The integral of a constant times a function is the constant times the integral of the function:
∫(−u4)du=−∫u4du
-
The integral of un is n+1un+1 when n=−1:
∫u4du=5u5
So, the result is: −5u5
Now substitute u back in:
−5cos5(x)
So, the result is: −532cos5(x)
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The integral of a constant times a function is the constant times the integral of the function:
∫(−24sin(x)cos2(x))dx=−24∫sin(x)cos2(x)dx
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Let u=cos(x).
Then let du=−sin(x)dx and substitute −du:
∫u2du
-
The integral of a constant times a function is the constant times the integral of the function:
∫(−u2)du=−∫u2du
-
The integral of un is n+1un+1 when n=−1:
∫u2du=3u3
So, the result is: −3u3
Now substitute u back in:
−3cos3(x)
So, the result is: 8cos3(x)
The result is: −11512cos11(x)+128cos9(x)−128cos7(x)+5272cos5(x)−8cos3(x)
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Now simplify:
558(−320cos8(x)+880cos6(x)−880cos4(x)+374cos2(x)−55)cos3(x)
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Add the constant of integration:
558(−320cos8(x)+880cos6(x)−880cos4(x)+374cos2(x)−55)cos3(x)+constant
The answer is:
558(−320cos8(x)+880cos6(x)−880cos4(x)+374cos2(x)−55)cos3(x)+constant
The answer (Indefinite)
[src]
/ 11 5
| 7 3 9 512*cos (x) 272*cos (x)
| sin(8*x)*cos(3*x) dx = C - 128*cos (x) - 8*cos (x) + 128*cos (x) - ------------ + -----------
| 11 5
/
−22cos(11x)−10cos(5x)
8 8*cos(3)*cos(8) 3*sin(3)*sin(8)
-- - --------------- - ---------------
55 55 55
558−1105cos11+11cos5
=
8 8*cos(3)*cos(8) 3*sin(3)*sin(8)
-- - --------------- - ---------------
55 55 55
−558cos(3)cos(8)−553sin(3)sin(8)+558
Use the examples entering the upper and lower limits of integration.