How to represent polynomials with numeric vectors in R

Question

In R how would one represent polynomial expressions and do polynomial math with the numeric vector objects? For example:

x1 <- c(2,1)  # 2 + x
x2 <- c(         


        

Answer 1

Polynomial multiplication is the convolution of the coefficients

convolve(c(2,1),rev(c(-1,3)),type="open")
#[1] -2  5  3