1\3+1\15+1\35+1\63+1\99("\"是分数线)等于多少?请写出过程.

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1\3+1\15+1\35+1\63+1\99("\"是分数线)等于多少?请写出过程.

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