Question

[Đặng Văn Dũng]

A= 2/3.5 + 3/5.8 + 11/8.19 + 13/19.32 + 25/32.57 + 30/57.87

B= 1/2 + 1/6 + 1/12 + 1/20 + 1/30 + 1/42 + 1/56 + 1/72

Answer 1

[Vũ Công Minh]

B=(1-1/2)+(1/2-1/6)+(1/6-1/12)+(1/12-1/20)+....+(1/56-1/72) B=1-1/2+1/2-1/6+1/6-1/12+1/12-1/20+...+1/56-1/72 B=1-1/72=71/72