简便计算1990+19901990+199019901990 1——————————————— - ——1989+19891989+198919891989 1989
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简便计算1990+19901990+199019901990 1——————————————— - ——1989+19891989+198919891989 1989
简便计算
1990+19901990+199019901990 1
——————————————— - ——
1989+19891989+198919891989 1989
简便计算1990+19901990+199019901990 1——————————————— - ——1989+19891989+198919891989 1989
1990+19901990+199019901990 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
1990+19901990+199019901990 1
——————————————— - ——
1989+19891989+198919891989 1989
=1990(1+10001+100010001) 1
——————————————— - ——
1989(1+10001+100010001...
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1990+19901990+199019901990 1
——————————————— - ——
1989+19891989+198919891989 1989
=1990(1+10001+100010001) 1
——————————————— - ——
1989(1+10001+100010001) 1989
=1990/1989-1/1989
=1989/1989
=1
收起
1990(1+10001+100010001)/1989(1+10001+100010001)-1/1989
=1990/1989-1/1989
等于1989+19901990+199019901990
——————————————
1989+19891989+198919891989
原式=1+ [(1+10001+100010001)-100020003]/(1989+19891989+198919891989)
=1