作业帮(78.6-0.786*25+75%*21.4)*1997 如何计算?
来源：学生作业帮 编辑：作业帮 分类：数学作业 时间：2024/05/15 18:23:52
(78.6-0.786*25+75%*21.4)*1997 如何计算?
(78.6-0.786*25+75%*21.4)*1997
=(78.6×1-78.6×0.25+0.75×21.4)×1997
=[78.6×(1-0.25)+0.75×21.4]×1997
=(78.6×0.75+21.4×0.75)×1997
=0.75×(78.6+21.4)×1997
=75×1997
=149775
再问： =(78.6×0.75+21.4×0.75)×1997是什么意思？
再答： 前面1-0.25=0.75呀 78.6×0.75+21.4×0.75 =0.75(78.6+21.4) =0.75×100 =75
再问： 我的意思是：它本来不是+0.75×21.4吗？怎么变成了+21.4×0.75？
再答： 0.75×21.4 和21.4×0.75不是一样吗
=(78.6×1-78.6×0.25+0.75×21.4)×1997
=[78.6×(1-0.25)+0.75×21.4]×1997
=(78.6×0.75+21.4×0.75)×1997
=0.75×(78.6+21.4)×1997
=75×1997
=149775
再问： =(78.6×0.75+21.4×0.75)×1997是什么意思？
再答： 前面1-0.25=0.75呀 78.6×0.75+21.4×0.75 =0.75(78.6+21.4) =0.75×100 =75
再问： 我的意思是：它本来不是+0.75×21.4吗？怎么变成了+21.4×0.75？
再答： 0.75×21.4 和21.4×0.75不是一样吗