Here's how it breaks down:
* "mut-" is the root of the word "mutate," meaning to change or alter.
* "does not change" can be expressed as "unchanging" or "immutable," both of which derive from the root "mut-."
* "unchanging" is formed by adding the prefix "un-" (meaning not) to "changing," which is derived from "change."
* "immutable" is formed by adding the prefix "in-" (meaning not) and the suffix "-able" (meaning capable of) to "mutate."
Therefore, "mut-" is the common Latin root that signifies "change" and is present in both "unchanging" and "immutable."