the factor of (a+b)^n-(a^n+b^n) is
a
b
ab
none
You have now posted 10 consecutive problems with not even an attempt to solve any. When people respond with hints, you say you don't understand and ask for the complete solution. If you don't understand even the hints, perhaps the course you are taking is too advanced for you. In any case, you do not learn by having other people do the problems for you. TRY!