Question

奥数 二分之一加三分之一加四分之一加五分之一……加十分之一怎么做

Answer 1

用加法结合率,先分别加1/2+1/4+1/8、1/3+1/6+1/9、1/5+1/10
得7/8、11/18、3/10，再加7/8+3/10=47/40，再加47/40+11/18=643/360，
还有1/7没有加过，最后算643/360+1/7=4861/2520

Answer 2

1/2+1/3+1/4+1/5+1/6+1/7+1/8+1/9+1/10
=(1/2+1/3+1/6)+(1/4+1/5+1/10)+1/7+1/8+1/9
=1+11/20+1/8+1/7+1/9
=1+27/40+1/9+1/7
=1+283/360+1/7
=1+2341/2520
=4861/2520
我是老师 谢谢采纳

Answer 3

1/2+1/3+1/4+1/5+1/6+1/7+1/8+1/9+1/10
=(1/2+1/3+1/6)+(1/4+1/5+1/10)+1/7+1/8+1/9
=1+11/20+1/8+1/7+1/9
=1+27/40+1/9+1/7
=1+283/360+1/7
=1+2341/2520
=4861/2520
=1.93