  The classical Enestrom-Kakeya theorem establishes upper and lower bounds on
the zeros of a polynomial with positive coefficients that are explicit
functions of those coefficients. We establish a unifying framework that
incorporates this theorem and several similar ones as special cases, while
generating new theorems of a similar type. These establish zero inclusion and
exclusion regions consisting of a single disk or the union of several disks in
the complex plane. Our framework is built on two basic tools, namely a
generalization of an observation by Cauchy, and a family of polynomial
multipliers. Its approach is transparent and reduces algebraic manipulations to
a minimum.
