即1/2×(1-1/3)+1/2×(1/3-1/5)+……+1/2×[1/(2n-1)-1/(2n+1)]=17/351/2×[1-1/3+1/3-1/5+……+1/(2n-1)-1/(2n+1)]=17/351/2×[1-1/(2n+1)]=17/35n/(2n+1)=17/35所以35n=17(2n+1)35n=34n+17n=17