kof98combo教学:用简便方法计算:(a+b-c)(a-b-c)-(a-b-c)^2

来源:百度文库 编辑:高校问答 时间:2024/05/04 07:16:21
要详细的解题过程

(a+b-c)(a-b-c)-(a-b-c)^2
=(a-b-c)[(a+b-c)-(a-b-c)]
=(a-b-c)2b

(a+b-c)(a-b-c)-(a-b-c)^2
=(a+b-c)(a-b-c)-(a-b-c)(a-b-c)
=(a-b-c)[(a+b-c)-(a-b-c)]
=2b(a-b-c)
若再去括号,可得
2ab-2b^2-2bc

=(a-b-c)[a+b-c-(a-b-c)]
=(a-b-c)(2b)
=2ab-2b^2-2bc

(a+b-c)(a-b-c)-(a-b-c)^2
=(a-b-c)[(a+b-c)-(a-b-c)]
=(a-b-c)2b

(a+b-c)(a-b-c)-(a-b-c)^2
=(a-b-c)[(a+b-c)-(a-b-c)]
=(a-b-c)2b

=[(a-c)+b][(a-c)-b]-[(a-c)-b]^2
=(a-c)^2-b^2-(a-c)^2+2b(a-c)+b^2
=2ab-2bc