ELI5: Explain Like I'm 5

Hensel's lemma

Imagine you have two equations, A and B, and you want to find a solution for both of them. But solving both equations together seems very challenging, so instead you solve them separately.

Hensel’s Lemma is a tool that helps you do this by finding solutions for A and B separately and then combining them to get a solution for both together.

It works by using a special type of math called modular arithmetic. This is like counting but with a special rule that brings the numbers back to zero after a certain point.

Let’s say you are counting by threes in modular arithmetic. This means after you reach the number 9, you start back at zero. So 3 + 3 = 6 (because 9 + 3 = 0 in modular arithmetic), and 6 + 3 = 9 (which then becomes 0).

Hensel’s Lemma uses this idea to find solutions to equations. It breaks down the equation into smaller pieces and solves each one using modular arithmetic. Then it combines these solutions to get a solution for the whole equation.

This may sound tricky, but it can be very useful for solving complex equations that are otherwise impossible to solve. So Hensel’s Lemma is an important tool for mathematicians to use when they need to solve tough problems.