199.7*199.7-19.95*1999的简便方法

lihong76992022-10-04 11:39:541条回答

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丹老鼠 共回答了16个问题 | 采纳率93.8%
199.7*199.7-19.95*1999
=1997*0.1*1997*0.1-1995*0.01*1999
=0.1*0.1*1997*1997-0.01*1995*1999
=0.01*1997*1997-0.01*(1997-2)*(1997+2)
=0.01*【1997*1997-(1997*1997-2*2)】
=0.01*(1997*1997-1997*1997+4)
=0.04*4
=0.04
1年前

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