A=\(\frac{1}{11}+\frac{1}{12}+\frac{1}{13}+...+\frac{1}{70}\)
CMR \(\frac{4}{3}\) bé hơn A bé hơn 2,5.
Làm nhanh giùm mình!!!!!
Chứng minh rằn
\(\frac{4}{3}< \frac{1}{11}+\frac{1}{12}+\frac{1}{13}+...+\frac{1}{70}< 2,5\)
MÌNH CẦN RẤT GẤP. GIÚP MÌNH VỚI Ạ. CẢM ƠN.
Bài 1:
Chứng minh rằng:
\(\frac{1}{6}< \frac{1}{5^2}+\frac{1}{6^2}+\frac{1}{7^2}+...+\frac{1}{100^2}< \frac{1}{4}\)
Bài 2:
Cho \(A=\frac{1}{11}+\frac{1}{12}+\frac{1}{13}+...+\frac{1}{70}\)
CMR: \(a)A>\frac{4}{3}\); \(b)A< 2,5\)
Cho À = \(\frac{1}{11}+\frac{1}{12}+\frac{1}{13}+...+\frac{1}{70}\)
CMR: A > \(\frac{4}{3}\)
Ai làm đúng vầ nhanh mk cho 10 tick lun
Cho A=\(\frac{1}{11}+\frac{1}{12}+\frac{1}{13}+...+\frac{1}{70}.Chungminhrang\frac{4}{3}< A< \frac{5}{2}\)
Chứng minh :
1,C=\(\frac{1}{11}+\frac{1}{12}+\frac{1}{13}+...+\frac{1}{70}.C< \frac{3}{4}\)
2,D=\(\frac{1}{5^2}+\frac{1}{9^2}+...+\frac{1}{409^2}< \frac{1}{12}\)
3,E=\(\frac{5}{5.8.11}+\frac{5}{8.11.14}+...+\frac{5}{302.305.308}< \frac{1}{48}\)
Cho A = \(\frac{1}{11}+\frac{1}{12}+...+\frac{1}{70}\)
C/m \(\frac{4}{3}< A< 2,5\)
Cho \(A=\frac{1}{11}+\frac{1}{12}+...+\frac{1}{70}.\)
Chứng minh rằng:
\(\frac{4}{3}< A< 2,5\)
Cho \(A=\frac{1}{11}+\frac{1}{12}\)\(+\frac{1}{13}\)\(+....+\frac{1}{70}\)
CMR:\(\frac{4}{3}\)<A< 5/2
