应该是1/(1*3)+1/(3*5)+1/(5*7)+1/(7*9)+1/(9*11)+1/(11*13)吧1/(1*3)=(1/1-1/3)/21/(3*5)=(1/3-1/5)/2.1/(11*13)=(1/11-1/13)/2所以 原式=(1/1-1/3)/2+(1/3-1/5)/2+.+(1/11-1/13)/2=(1/1-1/13)/2=6/13