Here's the question you clicked on:
jacobian
compute the following integral
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?
i have it but the y are saying the final answer is |dw:1360697434010:dw|
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...
@experimentX ,@ZeHanz ,@phi help me pls
\[ \frac{2A \Delta k x \cos( kx) }{x} = 2A \Delta k \cos (kx)\]
by further simplifying i got this |dw:1360699433822:dw|
|dw:1360699738616:dw|
thanx for trying maybe they have made the mistake
i have class at 7 in the morning ... sorry ... i gotta sleep now!!