简便计算1990+19901990+199019901990 1——————————————— - ——1989+198
来源:学生作业帮 编辑:作业帮 分类:数学作业 时间:2024/08/30 06:49:12
简便计算
1990+19901990+199019901990 1
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1989+19891989+198919891989 1989
1990+19901990+199019901990 1
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1989+19891989+198919891989 1989
1990+19901990+199019901990 1
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1989+19891989+198919891989 1989
=[1990*(1+10001+100010001)]/[1989*(1+10001+100010001)]-1/1989
=1990/1989-1/1989
=(1990-1)/1989
=1989/1989
=1
——————————————— - ——
1989+19891989+198919891989 1989
=[1990*(1+10001+100010001)]/[1989*(1+10001+100010001)]-1/1989
=1990/1989-1/1989
=(1990-1)/1989
=1989/1989
=1