cho S = 1/51+1/52+...+1/100. CMR 7/12<S<5/6
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
1. Cho A = 1/2 . 3/4 . 5/6 .....99/100
Chứng minh A^2 < 1/101
1. Cho A = 1/2 . 3/4 . 5/6 .....99/100
Chứng minh A^2 < 1/101
C/M:
a) 1/2<1/51+1/52+..+1/100<1
b) 7/12<1/21+1/22+...+1/40<5/6
chứng minh
a) 1/2 < 1/51 + 1/52 +....+ 1/100 < 1
b) 7/12 < 1/21 + 1/22 + ...+ 1/40 < 5/6
CMR:\(\dfrac{7}{12}< \dfrac{1}{51}+\dfrac{1}{52}+...+\dfrac{1}{100}< \dfrac{5}{6}\)
giúp mk nhé
a)50+48+46+....+4-47-45-43....-1
b)1+2-3-4+5+6-7-8+9+10-11-12+....+50-51-52+53+54
tính nhanh
Cho \(A=\frac{1}{1.2}+\frac{1}{3.4}+\frac{1}{5.6}+....\frac{1}{99.100}.\)Chứng minh rằng:
a.\(A=\frac{1}{51}+\frac{1}{52}+\frac{1}{53}+....+\frac{1}{100}.\)
b.\(\frac{7}{12}< A< \frac{5}{6}.\)