The order of an ARIMA model is usually denoted by the notation ARIMA(p,d ... pure time delay for the effect of the ith input series is the numerator polynomial of the transfer function for the ith ...

We solve polynomials algebraically in order to determine the roots - where a curve cuts the \(x\)-axis. A root of a polynomial function, \(f(x)\), is a value for \(x\) for which \(f(x) = 0\).