(a-b)3=?请问(a-b)3立方,怎么算?
问题描述:
(a-b)3=?请问(a-b)3立方,怎么算?
答
(a-b)3
=(a-b)^2(a-b)
=(a^2-2ab+b^2)(a-b)
=a^3-3a^2b+2ab^2-b^3