用简便方法计算:1⼀(1*4)+1⼀(4*7)+1⼀(7*10)+.....+1⼀(97*100)

2024-12-28 07:21:32
推荐回答(2个)
回答1:

1/(1*4)+1/(4*7)+1/(7*10)+.....+1/(97*100)
=1/3( 1/1 - 1/4) + 1/3( 1/4 - 1/7) + 1/3( 1/7 - 1/10) + .....+ 1/3( 1/97 - 1/100)
=1/3(1 - 1/4 + 1/4 - 1/7 + 1/7 - 1/10 + .....+ 1/97 - 1/100)
=1/3(1- 1/100)
=33/100

回答2:

0.33