So sánh A và B biết rằng A=1/50+1/51+1/52+....+1/98+1/99
B=1/5+1/13+1/14+1/15+1/61+1/62+1/63.
Những câu hỏi liên quan
So sánh A và B. A=1/50+1/51+1/52+...+1/98+1/99
và B= 1/5+1/13+1/14+1/15+1/61?1/62+1/63.
cho A=1/11+1/12+1/13+1/14+...+1/50
so sánh A với 1/2
cho B=1/50+1/51+1/52+...+1/98+1/99
chứng minh rằng b <1/2
cho C=1/10+1/11+1/12+...+1/99+1/100
chứng tỏ C >1
a, Ta có: \(A=\frac{1}{11}+\frac{1}{12}+...+\frac{1}{50}=\left(\frac{1}{11}+\frac{1}{12}+...+\frac{1}{30}\right)+\left(\frac{1}{31}+\frac{1}{32}+...+\frac{1}{60}\right)\)
Nhận xét: \(\frac{1}{11}+\frac{1}{12}+....+\frac{1}{30}>\frac{1}{30}+\frac{1}{30}+...+\frac{1}{30}=\frac{20}{30}=\frac{2}{3}\)
\(\frac{1}{31}+\frac{1}{32}+...+\frac{1}{60}>\frac{1}{60}+\frac{1}{60}+...+\frac{1}{60}=\frac{20}{60}=\frac{1}{3}\)
\(\Rightarrow A>\frac{2}{3}+\frac{1}{3}=1>\frac{1}{2}\)
Vậy A > 1/2
b, Ta có: \(\frac{1}{50}>\frac{1}{100};\frac{1}{51}>\frac{1}{100};........;\frac{1}{99}>\frac{1}{100}\)
\(\Rightarrow B>\frac{1}{100}+\frac{1}{100}+...+\frac{1}{100}=\frac{50}{100}=\frac{1}{2}\)
Vậy B > 1/2
c, Ta có: \(C=\frac{1}{10}+\frac{1}{11}+\frac{1}{12}+...+\frac{1}{100}=\frac{1}{10}+\left(\frac{1}{11}+\frac{1}{12}+...+\frac{1}{100}\right)\)
Nhận xét: \(\frac{1}{11}+\frac{1}{12}+...+\frac{1}{100}>\frac{1}{100}+\frac{1}{100}+...+\frac{1}{100}=\frac{90}{100}=\frac{9}{10}\)
\(\Rightarrow C>\frac{1}{10}+\frac{9}{10}=\frac{10}{10}=1\)
Vậy C > 1
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so sánh A=1/5 +1/13+1/14+1/15+1/61+1/62+1/63 va F = 1004/2006
cho M=1/5+1/13+1/14+1/15+1/61+1/62+1/63. Hãy so sánh M với 1/2
So sánh:
A=1/50+1/51+1/52+.....+1/98+1/99
B=1/2
CHO S = 1/5 + 1/13 +1/14 +1/15 +1/61 +1/62 +1/63. HÃY SO SÁNH S VÀ 1/2
GIÚP MIH`, MIH` TICK NHA
S=1/5+(1/13+1/14+1/15)+(1/61+1/62+1/63)
suy ra S<1/5+1/12.3+1/60.3
S<1/5+1/4+1/20
S<1/2
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S=\(\frac{1}{5}\)+(\(\frac{1}{13}+\frac{1}{14}+\frac{1}{15}\)) + (\(\frac{1}{61}+\frac{1}{62}+\frac{1}{63}\))
=> S< \(\frac{1}{5}+\frac{1}{12}.3+\frac{1}{60}.3\)
S<\(\frac{1}{5}+\frac{1}{4}+\frac{1}{20}\)
=> S< \(\frac{1}{2}\)
Vậy S<\(\frac{1}{2}\)
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So sánh \(A=\frac{1}{5}+\frac{1}{13}+\frac{1}{14}+\frac{1}{15}+\frac{1}{61}+\frac{1}{62}+\frac{1}{63}\)VÀ \(B=\frac{1}{2}\)
\(A=\frac{1}{5}+\left(\frac{1}{13}+\frac{1}{14}+\frac{1}{15}\right)+\left(\frac{1}{61}+\frac{1}{62}+\frac{1}{63}\right)
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chứng minh rằng s=1/5+1/13+1/14+1/15+1/61+1/62+1/63<1/2
So sánh A và B: 15^100+1/15^99+1=A và B=14/99+1/14^98+1
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