Final answer:
The regular expression for the given language is (00|11)*(00|11).
Step-by-step explanation:
The regular expression for the given language would be (00|11)*(00|11). This expression matches strings that contain zeros and ones in doubles. The (00|11) part ensures that the string must start and end with double zeros or double ones, and the * indicates that there can be any number of occurrences of 00 or 11 in between.
For example, the string 0011 matches the regular expression because it starts and ends with double zeros and has no other occurrences of double zeros or double ones. On the other hand, the string 011 does not match because it does not start and end with double zeros or double ones.