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jacobian

  • 3 years ago

compute the following integral

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  1. jacobian
    • 3 years ago
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    |dw:1360696905475:dw|

  2. ZeHanz
    • 3 years ago
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    Do you mean:\[\int\limits_{k+\Delta k}^{k-\Delta k}A \cos(kx) dk\]In that case: A and x are considered to be constants, so you get:\[\left[ \frac{ A }{ x }\sin(kx) \right]_{k-\Delta k}^{k+\Delta k}\]Now subtitute values for k and subtract. On the other hand: shouldn't different variable names be used for the boundaries?

  3. jacobian
    • 3 years ago
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    i have it but the y are saying the final answer is |dw:1360697434010:dw|

  4. ZeHanz
    • 3 years ago
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    OK, let's try it:\[\frac{ A }{ x }(\sin((k+\Delta k)x)-\sin((k-\Delta k)x)\] To get further, you need to remember the formula of Simpson for the difference of two sine functions: sin(a)-sin(b)=2cos((a+b)/2)sin((a-b)/2), but I have not (yet) got that answer of yours...

  5. jacobian
    • 3 years ago
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    @experimentX ,@ZeHanz ,@phi help me pls

  6. experimentX
    • 3 years ago
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    \[ \frac{2A \Delta k x \cos( kx) }{x} = 2A \Delta k \cos (kx)\]

  7. jacobian
    • 3 years ago
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    by further simplifying i got this |dw:1360699433822:dw|

  8. experimentX
    • 3 years ago
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    |dw:1360699738616:dw|

  9. jacobian
    • 3 years ago
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    thanx for trying maybe they have made the mistake

  10. experimentX
    • 3 years ago
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    i have class at 7 in the morning ... sorry ... i gotta sleep now!!

  11. jacobian
    • 3 years ago
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    ok bye

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