计算1/(4*9)+1/(9*14)+1/(14*19)+…………+1/(284*289)+1/(289*5)1 1 1 1 1---------+---------+-----------+…………+---------------+--------------- 简便计算,4*9 9*14 14*19 284*289 289*5用 x/(y*z)1往右移一点

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计算1/(4*9)+1/(9*14)+1/(14*19)+…………+1/(284*289)+1/(289*5)1 1 1 1 1---------+---------+-----------+…………+---------------+--------------- 简便计算,4*9 9*14 14*19 284*289 289*5用 x/(y*z)1往右移一点

计算1/(4*9)+1/(9*14)+1/(14*19)+…………+1/(284*289)+1/(289*5)1 1 1 1 1---------+---------+-----------+…………+---------------+--------------- 简便计算,4*9 9*14 14*19 284*289 289*5用 x/(y*z)1往右移一点
计算1/(4*9)+1/(9*14)+1/(14*19)+…………+1/(284*289)+1/(289*5)
1 1 1 1 1
---------+---------+-----------+…………+---------------+--------------- 简便计算,
4*9 9*14 14*19 284*289 289*5
用 x/(y*z)
1往右移一点

计算1/(4*9)+1/(9*14)+1/(14*19)+…………+1/(284*289)+1/(289*5)1 1 1 1 1---------+---------+-----------+…………+---------------+--------------- 简便计算,4*9 9*14 14*19 284*289 289*5用 x/(y*z)1往右移一点
1/(4*9)+1/(9*14)+1/(14*19)+…………+1/(284*289)+1/(289*5)
=1/5(1/4-1/9+1/9-1/14+1/14-1/19).+1/284-1/289)+1/(289*5)
=1/5(1/4-1/289)+1/(289*5)
=1/5*(289-4)/(4*289)+1/(289*5)
=285/(4*5*289)+1/(289*5)
==289/(4*5*289)
=1/20