### 5.29.1 Polynomials of a single variable: poly1

A polynomial of one variable is represented either by a symbolic expression or by the list of its coefficients in decreasing powers order (dense representation). In the latter case, to avoid confusion with other kinds of list

- use `poly1[...]` as delimiters in inputs
- check for in Xcas output.

Note that polynomials represented as lists of coefficients are always written in decreasing powers order even if increasing power is checked in cas configuration.