求值(1/2+1/3+…+1/2012)*(1+1/2+1/3+…+1/2011)-(1+1/2+1/3+…+1/2012)*(1/2+1/3

问题描述:

求值(1/2+1/3+…+1/2012)*(1+1/2+1/3+…+1/2011)-(1+1/2+1/3+…+1/2012)*(1/2+1/3
求值(1/2+1/3+…+1/2012)*(1+1/2+1/3+…+1/2011)-(1+1/2+1/3+…+1/2012)*(1/2+1/3+…+1/2011)

为了书写简便,设1/2+1/3+……+1/2012=M,1/2+1/3+……+1/2011=N,则
原式=M*(1+N)-(1+M)*N
=M+M*N-N-M*N
=M-N
=1/2012