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:~ksoong | :~ksoong | ||
| + | Answer from Prof. MImi | ||
*In the step where you replaced -n by k, you forgot to replace the n inside the summation. Also, the first sum should then go from -2 to -infinity, instead of infinity. | *In the step where you replaced -n by k, you forgot to replace the n inside the summation. Also, the first sum should then go from -2 to -infinity, instead of infinity. | ||
*Actually, I do not see why you replaced -n by k in both sums. IN the first sum, you should have set k=n-2. In the second sum, you did not need to make any change of variable. | *Actually, I do not see why you replaced -n by k in both sums. IN the first sum, you should have set k=n-2. In the second sum, you did not need to make any change of variable. | ||
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*The simplification of the first summation following the arrow is incorrect: you would need to add two terms instead of just one. | *The simplification of the first summation following the arrow is incorrect: you would need to add two terms instead of just one. | ||
*The equality following the arrow is only valid when |z|>|a|.You must write this next to the equality! | *The equality following the arrow is only valid when |z|>|a|.You must write this next to the equality! | ||
| − | + | *This explanation would be much clearer if you had typed in your answer: this way I could make notes directly inside the computations and cross-out and replace stuff using different colors. | |
| − | + | ---- | |
| − | + | Anybody sees anything else? Do you have more questions? | |
---- | ---- | ||
Revision as of 14:05, 11 September 2010
I'm not sure if I've done this correctly in the first place. I would like your input before I actually attempt to inverse it.
Thank you. 
- EDIT: I have realized at least that my ROCs have been backwards. I had understood it as trying to make the 1/z term go to zero to converge. Well, that's wrong.
- ~ksoong
Answer from Prof. MImi
- In the step where you replaced -n by k, you forgot to replace the n inside the summation. Also, the first sum should then go from -2 to -infinity, instead of infinity.
- Actually, I do not see why you replaced -n by k in both sums. IN the first sum, you should have set k=n-2. In the second sum, you did not need to make any change of variable.
- The arrow in the middle of your computations, and the one towards the end should both be replaced by equal signs.
- The simplification of the first summation following the arrow is incorrect: you would need to add two terms instead of just one.
- The equality following the arrow is only valid when |z|>|a|.You must write this next to the equality!
- This explanation would be much clearer if you had typed in your answer: this way I could make notes directly inside the computations and cross-out and replace stuff using different colors.
Anybody sees anything else? Do you have more questions?
