计算:(1)-2xy(3x²y-4xy²);(2)(a-2b)(a²+2ab+4b²).

题目

计算:(1)-2xy(3x²y-4xy²);(2)(a-2b)(a²+2ab+4b²).

答案

:(1)-2xy(3x²y-4xy²);
=-6x^3y^2+8x^2y^3
(2)(a-2b)(a²+2ab+4b²).
=a^3+2a^2b+4ab^2-2a^2b-4ab^2-8b^3
=a^3-8b^3