一数学题急啊啊啊啊啊!！！！！！！

2/(1*3)+2/(3*5)+2/(5*7)......+2/(2n-1)(2n+1)的值为34/35
1-1/3+1/3-1/5+1/5+1/7.....1/(2n-1)+1/(2n+1)=34/35
2n/2n+1=34/35
n=17

原式=1/2×（1-1/3+1/3-1/5+1/5-1/7……+1/(2n-1)-1/(2n+1)）
=n/(2n+1)
n=17

裂项
=[1-1/3+1/3-1/5+。。。+1/(2n-1)-1/(2n+1)]/2
=[1-1/(2n+1)]/2=17/35
所以n=17

1/(1*3)+1/(3*5)+1/(5*7)......+1/(2n-1)(2n+1)=1/1-1/3+1/3-1/5+1/5-1/7+...+1/(2n-1)1/(2n+1)=1/1-1/(2n+1)=17/35
所以1/(2n+1）=18/35
2n+1=35/18
2n=17/18
n=17/36

1/(1*3)+.....1/(2n-1)(2n+1)化检得

1/2*（1/1-1/3+1/3-1/5+。。。。1/2n-1-1/2n+1)=1/2(1-1*2n+1)=17/35
所以得n=17

35

1/2(1-1/3+1/3-1/5+.....)=17/35
1-1/n=34/35