Integral of sin(log2(x))/x 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=log(2)log(x).
Then let du=xlog(2)dx and substitute dulog(2):
∫log(2)2sin(u)du
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The integral of a constant times a function is the constant times the integral of the function:
∫log(2)sin(u)du=log(2)∫sin(u)du
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The integral of sine is negative cosine:
∫sin(u)du=−cos(u)
So, the result is: −log(2)cos(u)
Now substitute u back in:
−log(2)cos(log(2)log(x))
Method #2
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Let u=x1.
Then let du=−x2dx and substitute −du:
∫usin(log(2)log(u1))du
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The integral of a constant times a function is the constant times the integral of the function:
∫−usin(log(2)log(u1))du=−∫usin(log(2)log(u1))du
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Let u=log(2)log(u1).
Then let du=−ulog(2)du and substitute −dulog(2):
∫log(2)2sin(u)du
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The integral of a constant times a function is the constant times the integral of the function:
∫(−log(2)sin(u))du=−log(2)∫sin(u)du
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The integral of sine is negative cosine:
∫sin(u)du=−cos(u)
So, the result is: log(2)cos(u)
Now substitute u back in:
log(2)cos(log(2)log(u1))
So, the result is: −log(2)cos(log(2)log(u1))
Now substitute u back in:
−log(2)cos(log(2)log(x))
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Now simplify:
−log(2)cos(log(2)log(x))
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Add the constant of integration:
−log(2)cos(log(2)log(x))+constant
The answer is:
−log(2)cos(log(2)log(x))+constant
The answer (Indefinite)
[src]
/
|
| /log(x)\
| sin|------|
| \log(2)/ /log(x)\
| ----------- dx = C - cos|------|*log(2)
| x \log(2)/
|
/
−log2cos(log2logx)
∫01xsin(log2logx)dx
=
−log(2)⟨−1,1⟩−log(2)
Use the examples entering the upper and lower limits of integration.