MathDB
CIIM 2011 Problem 3

Source:

June 9, 2016
CIIM 2011undergraduate

Problem Statement

Let f(x)f(x) be a rational function with complex coefficients whose denominator does not have multiple roots. Let u0,u1,...,unu_0, u_1,... , u_n be the complex roots of ff and w1,w2,...,wmw_1, w_2,..., w_m be the roots of ff'. Suppose that u0u_0 is a simple root of ff. Prove that k=1m1wku0=2k=1n1uku0. \sum_{k=1}^m \frac{1}{w_k - u_0} = 2\sum_{k = 1}^n\frac{1}{u_k - u_0}.