Cho A=(1/3)(4/6)(7/9)(10/12)....(208/210). Chứng minh A<1/25
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Cho A= 1/3*4/6*7/9*10/12*...*208/210 . Chứng minh A<1/25
Cho A=\(\frac{1}{3}.\frac{4}{6}.\frac{7}{9}.\frac{10}{12}...\frac{208}{210}\)
Chứng minh A<\(\frac{1}{25}\)
Cho A=\(\frac{1}{3}.\) \(\frac{4}{6}.\frac{7}{9}.\frac{10}{12}....\frac{208}{210}\)
Chứng minh rằng A<1/25
CMR: \(\dfrac{1}{3}.\dfrac{4}{6}.\dfrac{7}{9}.\dfrac{10}{12}...\dfrac{208}{210}< \dfrac{1}{25}\)
Có:
\(\dfrac{n}{n+2}< \dfrac{n-1}{n}\)(Vì
\(n^2< n^2+n-2\forall n>2\))
Nên ta có
\(F=\dfrac{1}{3}.\dfrac{4}{6}....\dfrac{208}{201}\)
\(\Rightarrow F< \dfrac{1}{3}.\dfrac{3}{4}.\dfrac{6}{7}...\dfrac{207}{208}\)
\(\Rightarrow F^2< \dfrac{1.4.7...208}{3.6.9.12...210}.\dfrac{1.3.6.9...207}{3.4.7.10.208}\)
\(\Rightarrow F^2=\dfrac{1}{210}.\dfrac{1}{3}\)
\(\Rightarrow F^2=\dfrac{1}{630}< \left(\dfrac{1}{25}\right)^2\)
Vậy F\(< \dfrac{1}{25}\)
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Cho A=\(\frac{1}{3}x\frac{4}{6}x\frac{7}{9}x.....x\frac{208}{210}\)
Chứng minh :A<\(\frac{1}{25}\)
cho A=\(\frac{1}{3}.\frac{4}{6}.\frac{7}{9}.\frac{10}{12}.....\frac{208}{210}\)
cmr: A<\(\frac{1}{25}\)
giúp mik với mik cần gấp
Cho A=\(\frac{1}{3}.\frac{4}{6}\frac{7}{9}.\frac{10}{12}...\frac{208}{210}\)
CMR: \(\frac{1}{52}
Cho A=\(\frac{1}{3}.\frac{4}{6}.\frac{7}{9}...\frac{208}{210},CMR:A< \frac{1}{25}\)
cho a=1/3*4/6*.....208/210
chung minh a<1/25