代数式。

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2 | 2012-11-22 19:58:29 | 显示全部楼层 |阅读模式

6c-2a-(a-c)=6c-3a+c=7c-3a,3b+[6c-2a-(a-c)]=3b+7c-3a,5a+{3b+[6c-2a-(a-c)]}=5a+3b+7c-3a=2a+3b+7c,5a+{3b+[6c-2a-(a-c)]}-[9a-(4b+c)]=2a+3b+7c-[9a-(4b+c)]=2a+3b+7c-9a+4b+c=-7a+7b+8cy-w-(x-v)=-(x-y)-(w-v)=8-6=2m^2-mn=21,mn-n^2=-15,所以.m^2-mn+mn-n^2=m^2-n^2 =21-15=6m^2-mn-(mn-n^2)=m^2-2mn+n^2=36...

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