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\(12^{18}=3^{18}.\left(2^2\right)^{18}=3^{18}.2^{36}\)
\(64^3.18^6=\left(2^6\right)^3.\left(3^2\right)^6.2^6=2^{18}.3^{12}.2^6=2^{24}.3^{12}\)
Rõ ràng \(3^{18}.2^{36}>2^{24}.3^{12}\) nên \(12^{18}>64^3.18^6\)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(\frac{12}{23}\) và \(\frac{1212}{2323}\)
Ta có: \(\frac{12}{23}=\frac{12.101}{23.101}=\frac{1212}{2323}\)
=> 2 phân số bằng nhau.
\(\frac{-3434}{4141}\) và \(\frac{-34}{41}\)
Ta có: \(\frac{-34}{41}=\frac{-34.101}{41.101}=\frac{-3434}{4141}\)
=> 2 phân số bằng nhau
So sánh:
12/23 = 1212/2323
-3434/4141 = -34/41
Nhận xét: ab/cd = ababab...(ab)=cdcdcd...(cd)
![](https://rs.olm.vn/images/avt/0.png?1311)
a)12/23=1212/2323 vì:
12/23=12.101/23.101=1212/2323
b)-3434/4141=-34/41 vì:
-3434/4141=-3434:101/4141:101=-34/41
=>ab/cd=ab.101/cd.101=abab/cdcd
![](https://rs.olm.vn/images/avt/0.png?1311)
\(\frac{13}{40}\)-> 40 - 13=37
\(\frac{12}{35}\)-> 35-12=23
Vậy \(\frac{13}{14}\)> \(\frac{12}{35}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
Ta có : 3411 = 1711.211 = 1711.2048
1714 = 1711.173 = 1711.4913
Vì :2048 < 4913
Nên : 3411 < 1714
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\(A=\frac{12}{5^{2012}}+\frac{18}{5^{2013}}\)
\(B=\frac{18}{5^{2012}}+\frac{12}{5^{2013}}\)
=> \(A=\frac{12}{5^{2012}}+\frac{12}{5^{2013}}+\frac{6}{5^{2013}}\)
\(B=\frac{12}{5^{2012}}+\frac{12}{5^{2013}}+\frac{6}{5^{2012}}\)
Mà \(\frac{6}{5^{2012}}>\frac{6}{5^{2013}}\)
=> \(B>A\)
Vậy B > A
Nhớ tk
![](https://rs.olm.vn/images/avt/0.png?1311)
chúng đều = nhau
a)12/23=1212/2323 =>= nhau
b)-3434/4141=--34/41=>= nhau
![](https://rs.olm.vn/images/avt/0.png?1311)
a)\(\dfrac{1212}{2323}=\dfrac{1212:101}{2323:101}=\dfrac{12}{23}\)
b)\(\dfrac{-3435}{4141}< \dfrac{-3434}{4141}=\dfrac{-3434:101}{4141:101}\)
Nhận xét:
\(\dfrac{\overline{abab}}{\overline{cdcd}}=\dfrac{\overline{ab}}{\overline{cd}}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(\frac{12}{11}=1+\frac{1}{11}\)
\(\frac{20}{19}=1+\frac{1}{19}\)
Ta thấy \(\frac{1}{11}>\frac{1}{19}\Rightarrow1+\frac{1}{11}>1+\frac{1}{19}\)
\(\Rightarrow\frac{12}{11}>\frac{20}{19}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
S = 40 + 41 + 42 + 43 + ........... + 435
=> 4S = 4.( 40 + 41 + 42 + 43 + ........... + 435 )
=> 4S = 41+42 + 43 + ... + 436
=> 3S = ( 41+42 + 43 + ... + 436 ) - ( 40 + 41 + 42 + 43 + ........... + 435 )
=> 3S = 436 - 40 = 436 - 1
Ta có : 436 - 1 = ( 43 )12 - 1 = 6412 - 1 < 6412
Vậy 3S < 6412
Bạn nhân 4S = 4( 40+41+......+435) = 41+42+43+......+436
Lấy 4S - S = 3S = 41+42+43+......+436- (40+41+42......+435) = 436- 1
3S = 436- 1 = (43)12-1 = 6412-1 < 6412
Ta có: `12 = 12`
Mà `34 < 64`
`=> 34^12 < 64^12`