# Polynomials of a single variable: poly1

### 5.27.1 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 lists:

- poly1[…] is used as delimiters for inputs and for text form output.
- ▯ … ▯ is used for 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 (see Section 2.5.7).