比较a^3-a^2b-3ab^2 与2ba^2-6ab^2+b^3的大小

a^3-a^2b-3ab^2 -(2ba^2-6ab^2+b^3)=a^3-a^2b-3ab^2 -2ba^2+6ab^2-b^3=a^3-3a^2b+3ab^2 -b^3=a^3-b^3-3a^2b+3ab^2 =(a-b)(a^2+ab+b^2)-3ab(a-b)=(a-b)(a^2-2ab+b^2)=(a-b)^3当a＞b时,a^3-a^2b-3ab^2＞2ba^2-6ab^2+b^...