So sanh 354 và 281
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Bài này được cái dễ lộn số =.=
Ta có :
\(B=\frac{352+353+354}{353+354+355}=\frac{352}{343+354+355}+\frac{353}{353+354+355}+\frac{354}{353+354+355}\)
Vì :
\(\frac{352}{343}>\frac{352}{353+354+355}\)
\(\frac{353}{354}>\frac{353}{353+354+355}\)
\(\frac{354}{355}>\frac{354}{353+354+355}\)
Nên \(\frac{352}{353}+\frac{353}{354}+\frac{354}{355}>\frac{352+353+354}{353+354+355}\)
Hay \(A>B\)
Vậy \(A>B\)
Chúc bạn học tốt ~
Ta có : \(B=\frac{352+353+354}{353+354+355}\)
\(\Rightarrow B=\frac{352}{353+354+355}+\frac{353}{353+354+355}+\frac{354}{353+354+355}\)
Ta có : \(\frac{352}{353}>\frac{352}{353+354+355}\)
\(\frac{353}{354}>\frac{353}{353+354+355}\)
\(\frac{354}{355}>\frac{354}{353+354+355}\)
Cộng vế theo vế, ta có : \(\frac{352}{353}+\frac{353}{354}+\frac{354}{355}>\frac{352+353+354}{353+354+355}\)
\(\Rightarrow A>B\)
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\(\dfrac{333}{337}=\dfrac{337}{337}-\dfrac{4}{337}=1-\dfrac{4}{337}\\ \dfrac{277}{281}=\dfrac{281}{281}-\dfrac{4}{281}=1-\dfrac{4}{281}\\ \)
Ta thấy : \(\dfrac{4}{337}< \dfrac{4}{281}\)
\(=>1-\dfrac{4}{337}>1-\dfrac{4}{281}\\ =>\dfrac{333}{337}>\dfrac{277}{281}\)
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a) \(3^{54}\)
\(2^{200}=4^{100}>3^{54}\)
\(\Rightarrow3^{54}< 2^{200}\)
b) \(15^{12}=3^{12}.5^{12}\)
\(1^3.125^3=\left(5^3\right)^3=5^9< 3^{12}.5^{12}\)
\(\Rightarrow15^{12}>1^3.125^3\)
c) \(78^{12}-78^{11}=78^{11}.\left(7-1\right)=78^{11}.6\)
\(78^{11}-78^{10}=78^{10}.\left(7-6\right)=78^{10}.6< 78^{11}.6\)
\(\Rightarrow78^{12}-78^{11}>78^{11}-78^{10}\)
d) \(72^{45}-72^{44}=72^{44}.\left(72-1\right)=72^{44}.72>27^{44}\)
\(\Rightarrow72^{45}-72^{44}>27^{44}\)
e) \(3^{39}=\left(3^3\right)^{13}=27^{13}>11^{11}\)
\(\Rightarrow3^{39}>11^{11}\)
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a : vì \(\dfrac{354}{758}< 1;\dfrac{123}{56}>1\\ \Rightarrow\dfrac{354}{758}< \dfrac{123}{56}\)
b:\(\dfrac{-18}{2021}< 0;\dfrac{75}{2022}>0\\ \Rightarrow\dfrac{-18}{2021}< \dfrac{75}{2022}\)
a) Do 354/758<1 ;123/56>1
=>354/758<123/56
b) -18/2021<0;72/2022>0
=>-18/2021<72/2022
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`@` `\text {Answer}`
`\downarrow`
Ta có:
\(333^{444}=\left(333^4\right)^{111}=\left(3^4\cdot111^4\right)^{111}=\left(81\cdot111^4\right)^{111}=81^{111}\cdot111^{444}\) `(1)`
\(444^{333}=\left(444^3\right)^{111}=\left(4^3\cdot111^3\right)^{111}=\left(64\cdot111^3\right)=64^{111}\cdot111^{333}\) `(2)`
Vì \(81>64\), \(444>333\)
`=>`\(81^{111}>64^{111},\) \(111^{444}>111^{333}\) `(3)`
Từ `(1), (2)` và `(3)`
`=>`\(333^{444}>444^{333}\)
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Tớ chỉ gợi ý thôi nha
Cậu thích làm cách nào thì làm 1 trong 2 thôi
Cách 1 : Quy đồng mẫu số
Cách 2 : Quy đồng tử số
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N/X(nhận xét) : ta thấy 2001/2001x2002=1/1x2002=1/2002
2002/2002x2003=1/1x2003=1/2003
vì 1/2002>1/2003 suy ra 2001/2001x2002>2002/2002x2003 ( cứ so sánh = phần bù đi nhé , cậu mà ko bt phần bù là gì thì tớ lạy cậu luôn đấy )
\(3^{54}=3^{2.27}=\left(3^2\right)^{27}=9^{27}\)
\(2^{81}=2^{3.27}=\left(2^3\right)^{27}=8^{27}\)
Vì 927 > 827 nên 354 > 281
3^54 VÀ 2^81
ta có : 3^54 =9^27
2^81 =8^27
=> 9^27>8^27 vậy 3^54>2^81