请教各位：2004.05×1997.05-2001.05×1999.05=？     巧算.

谢谢amyhuangli和fred妈妈.

引用:

原帖由 丑丑她妈 于 2008-9-24 14:25 发表

=(2001.05+3)x1997.05-2001.5x(1997.05+2)
=2001.05x1997.05+3x1997.05-2001.05x1997.05-2001.05x2
=3x1997.05-(1997.05+4)x2
=3x1997.05-1997.05x2-8
=1997.05-8
=1989.05

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