(a-b-c).(b+c-a)².(c-a+b)³=(a-b-c)(a-b-c)²*【-(a-b-c)³】=-(a-b-c)的6次方
(a-b-c).(b+c-a)².(c-a+b)³=(a-b-c)(a-b-c)²[-(a-b-c)³]=-(a-b-c)^6
