4a^2b+3ab+b^4+19ab^2+a^4-2a^2-b-c^4？？？我要步骤，3a^2b+3ab+b^4+a^2b+11ab^2+a^4+8ab^2-2a^2-b-c^43a^2b+a^2b+3ab+b^4+11ab^2+8ab^2+a^4-2a^2-b-c^44a^2b+3ab+b^4+19ab^2+a^4-2a^2-b-c^4