HM
2
K
Khách
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HM
2
11 tháng 6 2018
ta có: 298 < 2100
=> 298+1<2100+1
\(\Rightarrow\frac{2^{102}+1}{2^{98}+1}>\frac{2^{102}+1}{2^{100}+1}\)
13 tháng 4 2015
ta có \(A=\frac{1}{100}+\frac{1}{101}+...+\frac{1}{149}\)
ta thấy \(\frac{1}{100}=\frac{1}{100}\)
\(\frac{1}{101}<\frac{1}{100}\)
\(\frac{1}{102}<\frac{1}{100}\)
................................
\(\frac{1}{149}<\frac{1}{100}\)
\(\Rightarrow A=\frac{1}{100}+\frac{1}{101}+\frac{1}{102}+...+\frac{1}{149}<\frac{1}{100}+\frac{1}{100}+\frac{1}{100}+...+\frac{1}{100}\)
\(=\frac{49}{100}<\frac{1}{2}\)
vì \(A<\frac{49}{100}<\frac{1}{2}\Leftrightarrow A<\frac{1}{2}\)
KN
19 tháng 5 2019
\(A=\frac{1}{2}.\frac{3}{4}.\frac{5}{6}...\frac{99}{100}\)
\(\Rightarrow A>\frac{1}{2}.\frac{2}{3}.\frac{4}{5}...\frac{98}{99}\)
\(\Rightarrow A^2>\frac{1}{2}.\frac{2}{3}.\frac{3}{4}.\frac{4}{5}...\frac{98}{99}.\frac{99}{100}\)
\(\Rightarrow A^2>\frac{1}{100}=\frac{1}{10^2}\)
Vậy \(A>\frac{1}{10}\)
KN
19 tháng 5 2019
\(A=\frac{1}{2}.\frac{3}{4}.\frac{5}{6}...\frac{9999}{10000}\)
\(\Rightarrow A>\frac{1}{2}.\frac{2}{3}.\frac{4}{5}...\frac{9998}{9999}\)
\(\Rightarrow A^2>\frac{1}{2}.\frac{2}{3}.\frac{3}{4}.\frac{4}{5}...\frac{9998}{9999}.\frac{9999}{10000}\)
\(\Rightarrow A^2>\frac{1}{10000}=\frac{1}{100^2}\)
\(VayA>\frac{1}{100}=B\)
LH
12 tháng 6 2018
đặt \(S=1+\frac{1}{2}+\frac{1}{3}+...+\frac{1}{100}\)
\(2S=\frac{1}{2}+\frac{1}{3}+...+\frac{1}{100}+\frac{1}{101}\)
\(\Leftrightarrow2S-S=\left(\frac{1}{2}+\frac{1}{3}+...+\frac{1}{101}\right)-\left(1+\frac{1}{2}+\frac{1}{3}+...+\frac{1}{100}\right)\)
\(\Leftrightarrow S=\frac{1}{101}-1=-\frac{100}{101}\)
KT
0
8 tháng 2 2020
Câu 1 :
Ta có : \(A=\frac{10^{100}+1}{10^{101}+1}\)
\(\Rightarrow10A=\frac{10^{101}+10}{10^{101}+1}=\frac{10^{101}+1+9}{10^{101}+1}=1+\frac{9}{10^{101}+1}\)
Ta có : \(B=\frac{10^{101}+1}{10^{102}+1}\)
\(10B=\frac{10^{102}+10}{10^{102}+1}=\frac{10^{102}+1+9}{10^{102}+1}=1+\frac{9}{10^{102}+1}\)
Vì 10101+1<10102+1
\(\Rightarrow\frac{9}{10^{101}+1}>\frac{9}{10^{102}+1}\)
\(\Rightarrow1+\frac{9}{10^{101}+1}>1+\frac{9}{10^{102}+1}\)
\(\Rightarrow\)10A>10B
\(\Rightarrow\)A>B
Vậy A>B.
8 tháng 2 2020
Câu 2 :
Ta có : \(E=\frac{2000+2001}{2001+2002}=\frac{2000}{2001+2002}+\frac{2001}{2001+2002}\)
Vì 2001<2001+2002 và 2002<2001+2002
\(\Rightarrow\hept{\begin{cases}\frac{2000}{2001}>\frac{2000}{2001+2002}\\\frac{2001}{2002}>\frac{2001}{2001+2002}\end{cases}}\)
\(\Rightarrow C>E\)
Vậy C>E.
KS
1
30 tháng 3 2020
Ta có A = \(\frac{10^{100}-1}{10^{98}-1}=\frac{10^{98}.10^2-10^2+99}{10^{98}-1}\)
\(=\frac{10^2\left(10^{98}-1\right)+99}{10^{98-1}}\)
\(=10^2+\frac{99}{10^{98}-1}\)
B= \(\frac{10^{101}-1}{10^{99}-1}=\frac{10^{99}.10^2-10^2+99}{10^{99}-1}\)
\(=\frac{10^2\left(10^{99}-1\right)+99}{10^{99}-1}\)
\(=10^2+\frac{99}{10^{99}-1}\)
Vì \(\frac{99}{10^{98}-1}>\frac{99}{10^{99}-1}\)nên \(10^2+\frac{99}{10^{98}-1}>10^2+\frac{99}{10^{99}-1}\)=> A > B
Vậy A > B
( ghi lại đề )
Ta có :
\(\frac{1}{4}z=\frac{2^{100}+1}{2^{100}+4}=\frac{2^{100}+4-3}{2^{100}+4}=\frac{2^{100}+4}{2^{100}+4}-\frac{3}{2^{100}+4}=1-\frac{3}{2^{100}+4}\)
\(\frac{1}{4}t=\frac{2^{102}+1}{2^{102}+4}=\frac{2^{102}+4-3}{2^{102}+4}=\frac{2^{102}+4}{2^{102}+4}-\frac{3}{2^{102}+4}=1-\frac{3}{2^{102}+4}\)
Lại có :
\(\frac{3}{2^{100}+4}>\frac{3}{2^{102}+4}\)
\(\Leftrightarrow\)\(-\frac{3}{2^{100}+4}< -\frac{3}{2^{102}+4}\)
\(\Leftrightarrow\)\(1-\frac{3}{2^{100}+4}< 1-\frac{3}{2^{102}+4}\)
\(\Leftrightarrow\)\(\frac{1}{4}z< \frac{1}{4}t\)
\(\Leftrightarrow\)\(z< t\)
Vậy \(z< t\)
Chúc bạn học tốt ~
ta có: \(T=\frac{2^{102}+1}{2^{100}+1}=\frac{2^2.\left(2^{100}+1\right)-3}{2^{100}+1}=\frac{2^2.\left(2^{100}+1\right)}{2^{100}+1}-\frac{3}{2^{100}+1}\)\(=4-\frac{3}{2^{100}+1}\)
\(Z=\frac{2^{100}+1}{2^{98}+1}=\frac{2^2.\left(2^{98}+1\right)-3}{2^{98}+1}=4-\frac{3}{2^{98}+1}\)
\(\Rightarrow\frac{3}{2^{100}+1}< \frac{3}{2^{98}+1}\)
\(\Rightarrow4-\frac{3}{2^{100}+1}>4-\frac{3}{2^{98}+1}\)
\(\Rightarrow T>Z\)