B=1/1.2+1/3.4+1/5.6+...+1/99.100
=1-1/2+1/3-1/4+1/5-1/6+...+1/99-1/100
=(1+1/3+1/5+...+1/99)-(1/2+1/4+1/6+...+1/100)
=(1+1/2+1/3+1/4+1/5+1/6+...+1/99+1/100)-2(1/2+1/4+1/6+...+1/100)
=(1+1/2+1/3+1/4+...+1/100)-(1+1/2+1/3+..+1/50)
=1/51+1/52+1/53+..+1/100 (1)
A=1/51+1/52+1/53+..+1/100 (2)
(1),(2)=> A/B=1
Cho A = 1/51 + 1/52+ 1/53 +...+ 1/100
B = 1/1.2 + 1/3.4 +1/5.6+...+ 1/99.100
A/ B = ?
so sánh A và B . biết A= 1/1.2 + 1/3.4 + 1/5.6 + ......+ 1 / 99.100
B = 2021/ 51 + 2021/52 + 2021/53 + .... + 2021/100
so sánh A và B . biết A= 1/1.2 + 1/3.4 + 1/5.6 + ......+ 1 / 99.100
B = 2021/ 51 + 2021/52 + 2021/53 + .... + 2021/100
tinh: ( 1/52+ 1/51+ 1/53 + ...+ 1/100) : ( 1/1.2 + 1/3.4 + 1/5.6 + .... + 1/99.100 )
tinh: ( 1/52+ 1/51+ 1/53 + ...+ 1/100) : ( 1/1.2 + 1/3.4 + 1/5.6 + .... + 1/99.100 )
CHỨNG MINH:1/1.2+1/3.4+1/5.6+1/7.8+.......+1/99.100=1/51+1/52+1/53+......+1/100
tính B:C biết
B=1/51+1/52+1/53+...+1/100
C= 1/1.2+1/3.4+1/5.6+...+1/99.100
Cho A = 1/1.2+1/3.4+1/5.6+...+1/99.100
a Chứng minh A= 1/51+1/52+1/53+...+1/100
b Chứng minh 7/12<A<5/6
Tính E=\(\frac{\frac{1}{51}+\frac{1}{52}+\frac{1}{53}+....+\frac{1}{100}}{\frac{1}{1.2}+\frac{1}{3.4}+\frac{1}{5.6}+....+\frac{1}{99.100}}\)
