Compute a polynomial via a product Given n+1 roots r0,r1,,rn of a polynomial p(x) of degree n+1,p(x) can be computed by p(x)=i=0n(xri)=(xr0)(xr1)(xrn1)(xrn). Write a function poly ( roots, x) that takes a list roots of the roots and x as arguments and returns p(x). [This assignment is based on Langtangen, Exercise 3.10.]