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30 tháng 7 2018

 So sánh :1780 và 6360

Ta có: 1780=1720.4=(174)20=8352120

   6360=6320.3=(633)20=25004720

vì 8352120<25004720

Nên 1780<6360

30 tháng 7 2018

a)\(4^{72}=\left(4^3\right)^{24}=64^{24}\)

\(8^{48}=\left(8^2\right)^{24}=64^{24}\)

\(\Rightarrow4^{72}=8^{48}\)

30 tháng 7 2018

a) \(4^{72}=\left(2^2\right)^{72}=2^{144}\)

\(8^{48}=\left(2^3\right)^{48}=2^{144}\)

mà \(2^{144}=2^{144}\)=> \(4^{72}=8^{48}\)

b) \(2^{252}=\left(2^2\right)^{126}=4^{126}\)

mà \(4^{126}< 5^{127}\)=> \(5^{127}>2^{252}\)

2 tháng 8 2018

KO AI TRẢ LỜI THẾ MH TRẢ LỜI LUN !

\(a,4^{72}v\text{à}8^{48}\)

TA CÓ:\(4^{72}=\left(2^2\right)^{72}=2^{144}\)

\(8^{48}=\left(2^3\right)^{48}=2^{144}\)

\(\Rightarrow4^{72}=8^{48}\)

\(b,5^{127}v\text{à}2^{254}\)

TA CÓ:\(2^{252}2^{2\times127}=\left(2^2\right)^{127}=4^{127}\)

\(5^{127}>4^{127}\left(v\text{ì5>4}\right)\)\(5^{127}>4^{127}\left(v\text{ì}5>4\right)\)

\(\Rightarrow5^{127}>2^{254}\)

2 tháng 8 2018

a) Ta có : 472 = 43.24 = (43)24 = 6424

                848 = 82.24 = (82)24 = 6424

Ta thấy : 6424 = 6424 => 472 = 848

b) Ta có : 2254 = 22.127 = (22)127 = 4127

Vì 5 > 4 => 5127 > 2254

a,ta có:

\(3^5.5^7.5.3^2\)

\(=\left(3^5.3^2\right).\left(5.5^7\right)\)

\(=3^7.5^8\)

\(b=2^8.\left(2.2\right)^5.9^9\)

\(=2^8.2^{10}.9^9\)

\(=2^{18}.9^9\)

21 tháng 12 2018

\(a,27^{11}=\left(3^3\right)^{11}=3^{33}\)

\(81^8=\left(3^4\right)^8=3^{32}\)

Vì \(3^{33}>3^{32}\) nên  \(27^{11}>81^8\)

\(b,625^5=\left(5^4\right)^5=5^{20}\)

\(125^7=\left(5^3\right)^7=5^{21}\)

Vì \(5^{20}< 5^{21}\) nên \(625^5< 125^7\)

23 tháng 7 2018

\(18^{20}.45^5.5^{25}.8^{10}\)

\(=3^{40}.2^{20}.5^5.3^{10}.5^{25}.2^{30}\)

\(=3^{50}.2^{50}.5^{30}\)

\(=6^{50}.5^{30}\) 

\(=\left(6^5\right)^{10}.\left(5^3\right)^{10}\)

\(=\left(6^5.5^3\right)^{10}\)

\(\left(x^2y\right)^5.\left(x^2.y^2\right)^7.\left(x.y\right)^6.x^3\)

\(=x^{10}.y^5.x^{14}.y^{14}.x^6.y^3.x^3\)

\(=x^{33}.y^{22}\)

\(=\left(x^3\right)^{11}.\left(y^2\right)^{11}\)

\(=\left(x^3.y^2\right)^{11}\)

\(2^7.3^8.4^9.9^8\)

\(=2^7.3^8.2^{18}.3^{16}\)

\(=2^{25}.3^{24}\)( mk chỉ làm được đến thế thôi )

Tham khảo nhé~

23 tháng 7 2018

a) \(18^{20}.45^5.5^{25}.8^{10}\)

\(=\left(2.3^2\right)^{20}.\left(3^2.5\right)^5.5^{25}.\left(2^3\right)^{10}\)

\(=2^{20}.3^{40}.3^{10}.5^5.5^{25}.2^{30}\)

\(=2^{50}.3^{50}.5^{30}\)

\(=6^{50}.5^{30}\)

\(=\left(6^5\right)^{10}.\left(5^3\right)^{10}\)

\(=7776^{10}.125^{10}\)

\(=972000^{10}\)

b ) \(\left(x^2y\right)^5.\left(x^2.y^2\right)^7.\left(xy\right)^6.x^3\)

\(=x^{10}.y^5.x^{14}.y^{14}.x^6.y^6.x^3\)

\(=x^{33}.y^{25}\)

\(=x^{25}.y^{25}.x^8\)

\(=...\)

c)  \(2^7.3^8.4^9.9^8\)

\(=2^7.3^8.\left(2^2\right)^9.\left(3^2\right)^8\)

\(=2^7.3^8.2^{18}.3^{16}\)

\(=2^{25}.3^{24}\)

\(=...\)( Câu c này hình như đề bài sai sót . Không chuyển thành lũy thừa được )

30 tháng 7 2018

\(2^{2464}>2^{2463}=\left(2^3\right)^{821}=8^{821}\)

Có \(8^{821}>7^{821}\)

\(\Rightarrow2^{2464}>7^{821}\)

8 tháng 4 2018

Ta có \(\frac{1}{9S}=\frac{9^{2017}+\frac{1}{9}}{9^{2017}+1}\)=   \(\frac{9^{2017}+1-\frac{8}{9}}{9^{2017}+1}=1-\frac{\frac{8}{9}}{9^{2017}+1}\)

           \(\frac{1}{9M}=\frac{9^{2016}+\frac{1}{9}}{9^{2016}+1}\)=    \(\frac{9^{2016}+1-\frac{8}{9}}{9^{2016}+1}=1-\frac{\frac{8}{9}}{9^{2016}+1}\)

Vì \(9^{2016}+1< 9^{2017}+1\)=> \(\frac{\frac{8}{9}}{9^{2016}+1}>\frac{\frac{8}{9}}{9^{2017}+1}\)

=> \(1-\frac{\frac{8}{9}}{9^{2016}+1}< 1-\frac{\frac{8}{9}}{9^{2017}+1}\)=>  \(\frac{1}{9}S< \frac{1}{9}M\Rightarrow S< M\)

a) Cách 1: \(\left(3^2\right)^3=3^{2.3}=3^6\)

\(\left(3^3\right)^2=3^{3.2}=3^6\)

\(\left(3^2\right)^5=3^{2.5}=3^{10}\)

\(9^8=\left(3^2\right)^8=3^{2.8}=3^{16}\)

\(27^6=\left(3^3\right)^6=3^{3.6}=3^{18}\)

\(81^{10}=\left(3^4\right)^{10}=3^{4.10}=3^{40}\)

Cách 2: \(\left(3^2\right)^3=9^3\)

\(\left(3^3\right)^2=3^{3.2}=\left(3^2\right)^3=9^3\)

\(\left(3^2\right)^5=9^5\)

\(9^8\)

\(27^6=\left(3^3\right)^6=3^{3.6}=3^{18}=3^{2.9}=\left(3^2\right)^9=9^9\)

\(81^{10}=\left(9^2\right)^{10}=9^{2.10}=9^{20}\)

Trả lời : 

b)

Ta có : \(5^{28}=5^{2.14}=\left(5^2\right)^{14}=25^{14}< 26^{14}\)

\(\Rightarrow5^{28}< 26^{14}\)