1/2+2/3+3/4+4/5=?

问题描述:

1/2+2/3+3/4+4/5=?

原式=1-1/2+1-1/3+1-1/4+1-1/5 =4-1/2-1/3-1/4-1/5 =4-(1/2+1/3+1/4+1/5) =4-(5/6+11/20) =4-122/120 =4-61/60 =179/60