=2ab×(8b^3+21-8b)+4b^2×(8b^3+21-8b)-3ab×(8b^3+21-8b)-3 (8b^3+21-8b)+4b^3/b×(8b^3+21-8b)=
=16ab^5+42ab^2-16ab^3+32b^5+84b^5-32b^2-24ab^4-64ab+24ab^4-63ab+24b^3-63+24b+4b^4/8b^4+24b-8b^2=
=16ab^5+66ab^2-16ab^3+32b^5+84b^2-56b^3-24b^4-63ab-63+24b+4b^4/8b^4-8b^2+21b.
