一道小学六年级的数学题,帮帮忙啊!!

=1/2（1-1/3）+1/2（1/3-1/5）+1/2（1/5-1/7）+1/2（1/7-1/9）+1/2（1/9-1/11）
=1/2-1/22
=5/11

1/3+1/15+1/35+1/63+1/99
=1/3×2+1/15×2+1/35×2+1/63×2+1/99×2
=(2/3+2/15+2/35+2/63+2/99)÷2=(1-1/3+1/3-1/5+1/5-1/7+1/7-1/9+1/9-1/11)÷2=10/11÷2=5/11

我们刚做过的,应该不会错,用抵消的方法.

1/3+1/15+1/35+1/63/+1/99
=1/3(1+1/5)+1/7(1/5+1/9)+1/99
=2/5+2/45+1/99
=4/9 +1/99
=45/99

简单