如题所述
第1个回答 2007-12-14
原式=[a+(b+c)][a-(b+c)] 想办法“凑”成(x-y)(x+y)的形式
=a方-(b+c)方
=a方-(b方+2bc+c方)
=a方-b方-c方-2bc
=a方-(b+c)方
=a方-(b方+2bc+c方)
=a方-b方-c方-2bc
第2个回答 2007-12-14
（a+b+c)(a-b-c)
=[a+(b+c)][a-(b+c) ]
=a^2-(b+c)^2
=a^2-(b^2+2bc+c^2)
=a^2-b^2-c^2-2bc本回答被提问者采纳
=[a+(b+c)][a-(b+c) ]
=a^2-(b+c)^2
=a^2-(b^2+2bc+c^2)
=a^2-b^2-c^2-2bc本回答被提问者采纳
第3个回答 2007-12-21
解：原式=a^2-b^2-b^2-bc-bc-c^2+a^2-c^2
=2a^2-2b^2-2bc-c^2
=2a^2-2b^2-2bc-c^2
第4个回答 2007-12-14
原式=(a+b+c)[a-(b+c)]
=a^2-(b+c)^2
=a^2-b^2-2bc-c^2
=a^2-(b+c)^2
=a^2-b^2-2bc-c^2
第5个回答 2007-12-14
A方-B方-C方-2BC
