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Cho A=\(\frac{1}{11}+\frac{1}{12}+\frac{1}{13}+...+\frac{1}{70}.Chungminhrang\frac{4}{3}< A< \frac{5}{2}\)
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!!!!!
Cho D=\(\frac{1}{11}+\frac{1}{12}+\frac{1}{13}+...+\frac{1}{70}\)
CMR:\(\frac{4}{3}< D< 2,5\)
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
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: \(a)A>\frac{4}{3}\); \(b)A< 2,5\)
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=\(\frac{5}{5.8.11}+\frac{5}{8.11.14}+...+\frac{5}{302.305.308}< \frac{1}{48}\)
A=\(\frac{1}{11}+\frac{1}{12}+\frac{1}{13}+.....+\frac{1}{70}\)
CM\(\frac{4}{3}< A< \frac{46}{15}\)
A=\(\frac{1}{11}+\frac{1}{12}+\frac{1}{13}+\frac{1}{14}+...+\frac{1}{70}\)
Chứng minh rằng:\(\frac{4}{3}< A< 35\)
Tính:
1,\(\frac{2}{5}+\left(-\frac{4}{5}\right)+\left(-\frac{1}{2}\right)\)
2,\(A=\frac{0,375-0,3+\frac{3}{11}+\frac{3}{12}}{-0,625+0,5-\frac{5}{11}-\frac{5}{12}}+\frac{1,5+1-0,75}{2,5+\frac{5}{3}-1,25}\)
3,\(B=\frac{\frac{1}{3}-\frac{1}{7}-\frac{1}{13}}{\frac{2}{3}-\frac{2}{7}-\frac{2}{13}}.\frac{\frac{1}{3}-0,25+0,2}{1\frac{1}{6}-0,875+0,7}+\frac{6}{7}\)