Recent content by nate9228

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    Complex analysis proof with residue theorem, argument principle

    Wow, the code did not turn out at all how I thought it was going to. I apologize for this confusion; I used the symbols button and just assumed they would translate to standard notation.
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    Complex analysis proof with residue theorem, argument principle

    Homework Statement Let C be a regular curve enclosing the distinct points w1,..., wn and let p(w)= (w-w1)(w-w2)...(w-wn). Suppose that f(w) is analytic in a region that includes C. Show that P(z)= (1/2\pii)∫(f(w)\divp(w))\times((p(w)-p(z)\div(w-z))\timesdw is a polynomial of degree n-1...
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    Partial fraction decomposition: One quick question

    Homework Statement Give the partial fraction decomposition of 1/z4+z2 Homework Equations The Attempt at a Solution My question is about the final answer. The book gives the answer to be 1/z2+ 1/2i(z+i)- 1/2i(z-i). For my answer I keep getting a negative for both of the 1/2i...
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    Prove sin(z1+z2)= sin(z1)cos(z2)+sin(z2)cos(z1), why this way?

    Homework Statement What I had to prove was sin(z1+z2)= sin(z1)cos(z2)+sin(z2)cos(z1). I did this simply using the e function definitions for sin and cos and it turned out fine. I then flipped to the back of my book to double check and they have a completely different method for proving it. The...
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    Integral question for cos(2z) in complex analysis

    One last comment.. just because I realized the source of both our confusions as to what the other was doing. I was looking at the limit of integration wrong. Like utterly wrong lol. I thought it was pi divided by the quantity 2+i, when really, as you elucidated, it is (pi/2)+i. That is why I was...
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    Integral question for cos(2z) in complex analysis

    Sorry, I was at a loss earlier and did that based on what a friend said because I had no idea. It did make sense to me though so it was my own error. In regards to the arithmetic: I was under the impression when you have i in the denominator, to put the fraction in a+bi form, you multiply the...
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    Integral question for cos(2z) in complex analysis

    I did (pi/2+i)*(2-i)/(2-i)= (2pi-ipi)/5... specifically the 5 came from (2+i)(2-i)=(2^2)-i^2=5. I then took (2pi-ipi)/5 and plugged it in for z in the formula, which then has it being multiplied by 2i, and 2i*(2pi-ipi)/5= (4ipi+2pi)/5. Sorry for leaving all of that out.
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    Integral question for cos(2z) in complex analysis

    I did (pi/2+i)*(2-i)/(2-i)= (2pi-ipi)/5... specifically the 5 came from (2+i)(2-i)=(2^2)-i^2=5. I then took (2pi-ipi)/5 and plugged it in for z in the formula, which then has it being multiplied by 2i, and 2i*(2pi-ipi)/5= (4ipi+2pi)/5. Sorry for leaving all of that out.
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    Integral question for cos(2z) in complex analysis

    Alright I figured it was that formula. So (1/2)sin(2z) becomes (1/4i)(e^(2iz)-e^(-2iz)). Yes I do know how to do complex exponentials , but not very well at a practical level yet. I did take the i out of the denominator of 2+i (using the conjugate) and then after putting into the formula I have...
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    Integral question for cos(2z) in complex analysis

    Homework Statement Evaluate ∫cos(2z)dz from pi/2 to pi/2+i Homework Equations The Attempt at a Solution I know the cos function is entire, thus independent of path and I just need to evaluate the end points. I also know when you integrate you get (1/2)sin2z. My only question is...
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    Complex analysis help please (just a quadratic proof)

    Ahh is it that I improperly multiplied the 4 through the equations? I think I should have multiplied through before I made the terms into squares, which would change for example 4y into 2y, etc.
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    Complex analysis help please (just a quadratic proof)

    Can you be more specific in regards to which part of my previous answer was wrong? Just so I know which part to look at. I see that I gave the ordered pair for the center backwards i.e (y,x) when it should be (x,y). I am not sure what you mean by handling the factor of 4 wrong though.
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    Complex analysis help please (just a quadratic proof)

    Oh yeah, definitely a circle and if I remember the rules properly it is centered at (2Im(A), -2Re(A)) and r= √\left|A^2\right|-4B
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    Complex analysis help please (just a quadratic proof)

    Alrighty. So now I have, after correcting the Re(Az) error and a little simplifying to get the 2's out of the denominators as well as producing the required 4B, (4y-2Im(A))2+ (4x+ 2Re(A))2= (ReA)2+ (ImA)2- 4B = \left|A^2\right|-4B. Since the LHS is greater then or equal to 0 the RHS must be the...
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