1⼀2+1⼀6+1⼀12+1⼀20+.........+1⼀90=?

2025-02-08 14:07:02
推荐回答(3个)
回答1:

1/2+1/6+1/12+1/20+.........+1/90
=1/1*2+1/2*3+1/3*4+1/4*5+...+1/9*10
=1-1/2+1/2-1/3+1/3-1/4+1/4-1/5+...+1/9-1/10
=1-1/10
=9/10

回答2:

1/2+1/6+1/12+1/20+.........+1/90
=1-1/2+1/2-1/3+...+1/9-1/10
=1-1/10
=9/10

回答3:

1-1/2+1/2-1/3+1/3-1/4+1/4.......+1/89-1/89+1/90
=1+1/90
=91/90