Question

三项的裂项1/(1*2*3)+1/(2*3*4)+1/(3*4*5)+.怎么裂项?

Answer 1

1/[n*(n+1)*(n+2)]=1/2*{1/[n*(n+1)]-1/[(n+1)*(n+2)]}

求和等于：1/2{1/2-1/[(n+1)*(n+2)]}