MathDB
real analysis

Source: miklos schweitzer 2011 q8

August 29, 2021
real analysis

Problem Statement

Given a nonzero real number a1/ea\leq 1/e, let z1,...,znCz_1, ..., z_n \in C be non-real numbers for which zez+a=0ze^z + a = 0 holds, and let c1,...,cnCc_1, ..., c_n \in C be arbitrary. Show that the function f(x)=Re(j=1ncjezjx)f(x)=Re(\sum_{j=1}^n c_j e^{z_j x}) (xRx \in R) has a zero in every closed interval of length 1.