-a的三次方+2b的三次方-3ab+2=-()=2-a的三次方-()

问题描述:

-a的三次方+2b的三次方-3ab+2=-()=2-a的三次方-()

-a的三次方+2b的三次方-3ab+2=-(a³-2b³+3ab-2)=2-a的三次方-(3ab-2b³)