求2004.05×1997.05-2001.05×1999.05的简便方法
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![求2004.05×1997.05-2001.05×1999.05的简便方法](/uploads/image/z/745478-62-8.jpg?t=%E6%B1%822004.05%C3%971997.05%EF%BC%8D2001.05%C3%971999.05%E7%9A%84%E7%AE%80%E4%BE%BF%E6%96%B9%E6%B3%95)
求2004.05×1997.05-2001.05×1999.05的简便方法
求2004.05×1997.05-2001.05×1999.05的简便方法
求2004.05×1997.05-2001.05×1999.05的简便方法
2004.05×1997.05-2001.05×1999.05
=2004.05×1997.05-2001.05×1997.05-2001.05×2
=3×1997.05-2001.05×2
=3×1997.05-2001.05×(3-1)
=3×1997.05-2001.05×3+2001.05
=3×(1997.05-2001.05)+2001.05
=-12+2001.05
= 1989.05