(a-b)^3=a^3-3a^2b+3ab^2-b^3过程（a-b）^3 =（a-b）(a²-2ab+b²) =a³-2a²b+ab²-a²b+2ab²-b³ =a³-3a²b+3ab²-b³ 再送你一个:(a+b)^3+(a-b)^3=2a^3+6ab^2
(a-b)^3=a^3-3a^2 b+3ab^2-b^3
