2 câu trả lời
Đặt A=199+298+...
= 1/99 +2/98 + ... + 99
= (1/99 +1)+(2/98+1)+...+1
= 100/99 + 100/98 + ... + 100/100
= 100 (1/2+1/3+...+1/100)
Đặt B=1/2 +1/3+...+ 1/100
->A/B=(100(1/2+1/3+...+1/100))/(1/2+1/3+...+1/100)
->A/B=100
Đặt A=199+298+...
= 1/99 +2/98 + ... + 99
= (1/99 +1)+(2/98+1)+...+1
= 100/99 + 100/98 + ... + 100/100
= 100 (1/2+1/3+...+1/100)
Đặt B=1/2 +1/3+...+ 1/100
->A/B=(100(1/2+1/3+...+1/100))/(1/2+1/3+...+1/100)
->A/B=100