(a-2b+3c)(2b-a-3c)
问题描述:
(a-2b+3c)(2b-a-3c)
答
(a-2b+3c)(2b-a-3c)
=-[(a+3c)-2b][(a+3c)-2b]
=-[(a+3c)2-2•2b•(a+3c)+(2b)2]
=-a2-6ac-c2+4ab-12bc-4b2.