1/2*4+1/4*6+1/6*8+.......1/48*50
=1/2(1/2-1/4)+1/2(1/4-1/6)+1/2(1/6-1/8)+.....1/2(1/48-1/50)
=1/2(1/2-1/4+1/4-1/6+...+1/48-1/50)
=1/2(1/2-1/50)
=6/25
题目会否有误,原式是否就为:1/2*4+1/4*6+1/6*8+1/48*50=1/8+1/24+1/48+1/48×50=(6×50+2×50+50+1)/48×50=451/2400
2+3/2+4/3+25/24=141/24
3
141/24
有意思么?