1*3/1+3*5/1+5*7/1+……+(2n-1)(2n+1)/1=?

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1*3/1+3*5/1+5*7/1+……+(2n-1)(2n+1)/1=?1*3/1+3*5/1+5*7/1+……+(2n-1)(2n+1)/1=?1*3/1+3*5/1+5*7/1+……+(2n-1

1*3/1+3*5/1+5*7/1+……+(2n-1)(2n+1)/1=?
1*3/1+3*5/1+5*7/1+……+(2n-1)(2n+1)/1=?

1*3/1+3*5/1+5*7/1+……+(2n-1)(2n+1)/1=?
1*3/1+3*5/1+5*7/1+……+(2n-1)(2n+1)/1=?
分数是吧
表有问题啊
应该是1/1*3表示的是1*3分之1
1*3/1+3*5/1+5*7/1+……+(2n-1)(2n+1)/1
=1/2*[1/1-1/3+1/3-1/5+1/4-1/7+...+1/(2n-1)-1/(2n+1)]
=1/2*[1-1/(2n+1)]
=1/2*2n(2n+1)
=n/(2n+1)