Me pls! could u explain how to do it! in a simple way !

A) (x-c)²
= x²-2cx+c²
1. x×x = x²
2. 2×x×(-c) = -2cx
3. (-c)×(-c) = c²

b) (a-2b-c)²
= (a-2b-c)(a-2b-c)
= a²-2ab-ac-2ab+4b²+2bc-ca+2bc+c²
= a²-4ab-2ac+4b²+4bc+c²

This is what i found “an explicit formula designates the nth term of the sequence, as an expression of n (where n = the term's location). it defines the sequence as a formula in terms of n. this example is an arithmetic sequence(the same number, 5, is added to each term to get to the next term).” i hope this you for what your looking for. can you plz mark me brainliest?