Chứng minh rằng :\(\frac{1}{41}+\frac{1}{42}+\frac{1}{43}+...+\frac{1}{79}+\frac{1}{80}>\frac{7}{12}\)
Chứng tỏ rằng: \(\frac{1}{41}+\frac{1}{42}+\frac{1}{43}+...+\frac{1}{79}+\frac{1}{80}>\frac{7}{12}\)
Chứng minh
\(\frac{1}{41}+\frac{1}{42}+\frac{1}{43}+\frac{1}{44}+........................+\frac{1}{78}+\frac{1}{79}+\frac{1}{80}< \frac{1}{2}\)
Giúp mình nhé ai nhanh nhất mình tick
Chứng tỏ rằng :\(y=\frac{1}{41}+\frac{1}{42}+\frac{1}{43}+...+\frac{1}{79}+\frac{1}{80}>\frac{7}{12}\)
Chứng tỏ rằng:
a/ \(\frac{1}{2}< \frac{1}{41}+\frac{1}{42}+\frac{1}{43}+...+\frac{1}{80}< 1\)
b/ \(1< \frac{3}{10}+\frac{3}{11}+\frac{3}{12}+\frac{3}{13}+\frac{3}{14}< 2\)
c/ A=\(\frac{1}{2}+\frac{1}{2^2}+\frac{1}{2^3}+...+\frac{1}{2^{100}}< 1\)
d/ \(B=\frac{1}{3}+\frac{1}{3^2}+\frac{1}{3^3}+...+\frac{1}{3^{99}}< \frac{1}{2}\)
e/ \(\frac{2}{5}< \frac{1}{41}+\frac{1}{42}+\frac{1}{43}+...+\frac{1}{80}< \frac{2}{3}\)
f/\(C=\frac{3}{1^2\cdot2^2}+\frac{5}{2^2\cdot3^2}+\frac{7}{3^2\cdot4^2}+...+\frac{19}{9^2\cdot10^2}< 1\)
chứng tỏ rằng :
\(\frac{1}{41}+\frac{1}{42}+\frac{1}{43}+...+\frac{1}{79}+\frac{1}{80}>\frac{7}{12}\)
Cm: \(\frac{1}{41}+\frac{1}{42}+\frac{1}{43}+...+\frac{1}{79}+\frac{1}{80}>\frac{7}{12}\)
Chứng tỏ rằng:
\(\frac{1}{41}+\frac{1}{42}+\frac{1}{43}+...+\frac{1}{79}+\frac{1}{80}>\frac{7}{12}\)
a)\(\frac{1}{5^2}+\frac{1}{5^3}+\frac{1}{5^4}+......+\frac{1}{5^{2019}}< \frac{1}{2}\)
b) \(\frac{1}{2^2}+\frac{1}{3^3}+\frac{1}{4^3}+......+\frac{1}{4^2}< 1\)
c) \(\frac{1}{2}-\frac{1}{4}+\frac{1}{8}-\frac{1}{16}+\frac{1}{32}-\frac{1}{64}< \frac{1}{3}\)
d) \(\frac{1}{3}+\frac{2}{3^2}+\frac{3}{3^3}-\frac{4}{3^4}+......+\frac{99}{3^{99}}-\frac{100}{3^{100}}< \frac{3}{16}\)
e) \(\frac{1}{41}+\frac{1}{42}+\frac{1}{43}+\frac{1}{44}+.....+\frac{1}{79}+\frac{1}{80}>\frac{7}{12}\)
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