- #1
nateHI
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Homework Statement
For ##|z-a|<r## let ##f(z)=\sum_{n=0}^{\infty}a_n (z-a)^n##. Let ##g(z)=\sum_{n=0}^{\infty}b_n(z-a)^n##. Assume ##g(z)## is nonzero for ##|z-a|<r##. Then ##b_0## is not zero.
Define ##c_0=a_0/b_0## and, inductively for ##n>0##, define
$$
c_n=(a_n - \sum_{j=0}^{n-1} c_j b_{n-j})/b_0
$$
Note that the definition of ##c_n## implies that ##a_n=\sum_{j=0}^{n} c_j b_{n-j}## (it is equivalent to say ##c_n## solves this last equality)
So, we have a formal series (no claim yet on converging to ##f/g##), ##\sum_{n=0}^{\infty} c_n (z-a)^n##. Call this the formal quotient.
Take the formal quotient for granted. Prove that the formal quotient actually converges to ##f/g## for all ##|z-a|<r##
Homework Equations
The Attempt at a Solution
I'm stumped. Any ideas on how to get started showing this?[/B]