1/3+1/(3+3)+1/(3+3+5)+1/(3+3+5+7)+1/(3+3+5+7+9)+.+1/(3+3+5+7+.+2n_数学解答

1/3+1/(3+3)+1/(3+3+5)+1/(3+3+5+7)+1/(3+3+5+7+9)+.+1/(3+3+5+7+.+2n-1)

人气：475 ℃　时间：2020-04-24 01:13:00

解答

Step 1:第n项等于 1/(3+(2n-1))*((2n-1-3)/2-1)/2 = 1/(n^2+2)
Step 2:1/(n^2+2) < 1/ (n^2-1)
Step 3:1/ (n^2-1)