mathlib

742aa2cb - feat(data.polynomial.div): add `theorem X_pow_dvd_iff` (#18528)

feat(data.polynomial.div): add `theorem X_pow_dvd_iff` (#18528) Add the `theorem X_pow_dvd_iff` saying that a polynomial is divisible by $X^n$ if and only if its first $(n-1)$ coefficients are $0$.