分子是1分母分别是15,35,63,99和11的加法,简便方法怎么做?

2024-12-31 04:12:54
推荐回答(1个)
回答1:

1/15+1/35+1/63+1/99+1/11
=1/(3×5)+1/(5×7)+1/(7×9)+1/(9×11)+1/11
=1/2×(1/3-1/5)+1/2×(1/5-1/7)+1/2×(1/7-1/9)+1/2×(1/9-1/11)+1/11
=1/2×(1/3-1/5+1/5-1/7+1/7-1/9+1/9-1/11)+1/11
=1/2×(1/3-1/11)+1/11
=1/2×8/33+1/11
=7/33