经典小学数学问题..数学高手进

来源:百度知道 编辑:UC知道 时间:2024/05/15 08:04:59
1/1×1/4+1/4×1/7+1/7×1/10+1/10×1/13+.......1/94×1/97+1/97×1/100
谁能做出来..快快地...要用小学的简便方法做.详细点....

1-1/4=3/4
1/4-1/7=3/28
1/7-1/10=3/70
......
1/97-1/100=3/9700.
等号左右两边分别相加得:
1-1/4+1/4-1/7+......+1/97-1/100=1-1/100=99/100
=3*(1/4+1/28+1/70+......+1/9700)
=3*(1/1*1/4+1/4*1/7+1/7*1/10+......+1/97*1/100)
=99/100

所以原式1/1×1/4+1/4×1/7+1/7×1/10+1/10×1/13+.......1/94×1/97+1/97×1/100
=33/100

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

请给分

=33/100

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

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

1/1×1/4+1/4×1/7+1/7×1/10+1/10×1/13+.......1/94×1/97+1/97×1/100
=1/3×(1/1-1/4)+1/3×(1/4-1/7)+...1/3×(1/97-1/100)
=1/3×(1-1/4+1/4-1/7+1/7...-1/100)
=1/3×99/100
=33/100
=0.33