Hensel's lemma
A simple root over the residue field lifts to a root in a complete discrete valuation ring. Follow Newton's successive corrections, then compare the coprime-factor lifting form of Hensel's lemma.
Before opening the references
Where to read
Start here: Algebraic Number Theory (v3.08)
James S. Milne · Lecture notes · English · Free full text
Chapter 7, Newton's lemma, Proposition 7.31 (simple-root lifting), and Theorem 7.33 (Hensel's lemma, coprime-factor lifting), printed pp. 120–121
Continue from here
Algebraic Number Theory & Class Field Theory in the library · Preparation and skip guidance · Terminology and translation evidence