Question

cho A=\(1+\frac{1}{2}+\frac{1}{3}+...+\frac{1}{4026}\)

B=\(1+\frac{1}{3}+\frac{1}{5}+...+\frac{1}{4025}\)

so sánh \(\frac{A}{B}\)với \(1\frac{2013}{2014}\)

ai làm được 10 tích 

Answer 1

a = 1+ 1/2 +1/3+...+1/ 1025 + 1/1026

a= 1+ (1/12+1/3+....+1/1025) - (1/2+1/3+...+1/1025+ 1/1026)

a= 1+ (1/2- 1/1026)

a= 1+ 256/513

a= 283/171

ko chắc chắn

đúng k nha

Answer 2

Ta có:

AB=1+1/2+1/3+...+1/4026/1+1/3+1/5+1/7+...+1/4025

⇒AB=(1+1/3+1/5+...+1/4025)+(1/2+1/4+...+1/2046)1+1/3+1/5+...+1/4025

⇒AB=1+1/3+1/5+...+1/4025/1+1/3+1/5+....+1/4025+1/2+1/4+...+1/4026/1+1/3+1/5+...+1/4025

⇒AB=1+1/2+1/4+...+1/2046/1+1/3+1/5+...+1/4025

Dễ thấy AB>1

Mà 20132014<1