>>12289068Assuming this is in R (or C I guess, since the same field properties hold)
(x+1)(x+1)=x(x-1)+1(x-1), because of commutativity.
=x^2 - x +x - 1, again because of commutativity.
=x^2 + 0 - 1, since -x is the additive inverse of x so x + (-x) =0.
=x^2 - 1, since 0 is the additive identity
