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## Homework Statement

Let C be a regular curve enclosing the distinct points w

_{1},..., w

_{n}and let p(w)= (w-w

_{1})(w-w

_{2})...(w-w

_{n}). Suppose that f(w) is analytic in a region that includes C. Show that P(z)= (1/2[itex]\pi[/itex]i)∫(f(w)[itex]\div[/itex]p(w))[itex]\times[/itex]((p(w)-p(z)[itex]\div[/itex](w-z))[itex]\times[/itex]dw

is a polynomial of degree n-1 with P(w

_{k}) = f(w

_{k}), k= 1,2,...

## Homework Equations

## The Attempt at a Solution

So far I know this has something to do with the argument principle and possibly the residue theorem. I believe the inside of the integral reduces to (p'(w)[itex]\div[/itex]p(w))[itex]\times[/itex]f(w)dw, which is why I think the argument principle pertains to this problem. After this I am not sure what to do. This problem is from Bak and Newman Complex Analysis, third edition, chapter 10, if anyone is familiar with the book.