Integral of cos4x/(sqrtsin4x+1) dx
The solution
Detail solution
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There are multiple ways to do this integral.
Method #1
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Let u=4x.
Then let du=4dx and substitute du:
∫4sin(u)+4cos(u)du
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Let u=sin(u).
Then let du=2sin(u)cos(u)du and substitute du:
∫2u+2udu
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Rewrite the integrand:
2u+2u=21−2(u+1)1
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Integrate term-by-term:
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The integral of a constant is the constant times the variable of integration:
∫21du=2u
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The integral of a constant times a function is the constant times the integral of the function:
∫(−2(u+1)1)du=−2∫u+11du
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Let u=u+1.
Then let du=du and substitute du:
∫u1du
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The integral of u1 is log(u).
Now substitute u back in:
log(u+1)
So, the result is: −2log(u+1)
The result is: 2u−2log(u+1)
Now substitute u back in:
−2log(sin(u)+1)+2sin(u)
Now substitute u back in:
−2log(sin(4x)+1)+2sin(4x)
Method #2
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Let u=sin(4x).
Then let du=sin(4x)2cos(4x)dx and substitute du:
∫2u+2udu
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Rewrite the integrand:
2u+2u=21−2(u+1)1
-
Integrate term-by-term:
-
The integral of a constant is the constant times the variable of integration:
∫21du=2u
-
The integral of a constant times a function is the constant times the integral of the function:
∫(−2(u+1)1)du=−2∫u+11du
-
Let u=u+1.
Then let du=du and substitute du:
∫u1du
-
The integral of u1 is log(u).
Now substitute u back in:
log(u+1)
So, the result is: −2log(u+1)
The result is: 2u−2log(u+1)
Now substitute u back in:
−2log(sin(4x)+1)+2sin(4x)
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Add the constant of integration:
−2log(sin(4x)+1)+2sin(4x)+constant
The answer is:
−2log(sin(4x)+1)+2sin(4x)+constant
The answer (Indefinite)
[src]
/
| __________ / __________\
| cos(4*x) \/ sin(4*x) log\1 + \/ sin(4*x) /
| ---------------- dx = C + ------------ - ---------------------
| __________ 2 2
| \/ sin(4*x) + 1
|
/
∫sin(4x)+1cos(4x)dx=C−2log(sin(4x)+1)+2sin(4x)
The graph
________ / ________\
\/ sin(4) log\1 + \/ sin(4) /
---------- - -------------------
2 2
−2log(1+sin(4))+2sin(4)
=
________ / ________\
\/ sin(4) log\1 + \/ sin(4) /
---------- - -------------------
2 2
−2log(1+sin(4))+2sin(4)
sqrt(sin(4))/2 - log(1 + sqrt(sin(4)))/2
(-0.140934640209814 + 0.0771497634534624j)
(-0.140934640209814 + 0.0771497634534624j)
Use the examples entering the upper and lower limits of integration.