1X3分之1+3X5分之1十5X7分之1十…2011X2013分之1

你好！ 1/(1*3) + 1/(3*5) +1/(5*7) +……+1/(2011*2013) = 1/2*(1 - 1/3) + 1/2*(1/3 - 1/5) + 1/2*(1/5 - 1/7) +…… +1/2*(1/2011 - 1/2013) = 1/2 * ( 1 - 1/3 + 1/3 - 1/5 + 1/5 - 1