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12 tháng 9 2023

8⁵ = (2³)⁵ = 2¹⁵ = 2.2¹⁴

3.4⁷ = 3.(2²)⁷ = 3.2¹⁴

Do 2 < 3 nên 2.2¹⁴ < 3.2¹⁴

Vậy 8⁵ < 3.4⁷

12 tháng 9 2023

\(8^5=2^{15}=2.2^{14}\)

\(3.4^7=3.2^{14}>2.2^{14}\)

\(\Rightarrow8^5< 3.4^7\)

\(A=\frac{3}{8^3}+\frac{7}{8^4}=\frac{3}{8^3}+\frac{3}{8^4}+\frac{4}{8^4}\)

\(B=\frac{7}{8^3}+\frac{3}{8^4}=\frac{3}{8^3}+\frac{3}{8^4}+\frac{4}{8^4}\)

\(A=\frac{3}{8^3}+\frac{3}{8^4}+\frac{4}{8^3}>B=\frac{3}{8^3}+\frac{3}{8^4}+\frac{4}{8^4}\)

vậy A>B

22 tháng 2 2017

A=(24+7)/8^4 =31/8^4 
B=(56+3)/8^4 = 59/8^4 
=> A<B

`@` `\text {Ans}`

`\downarrow`

`1,`

`a)`

`3^12` và `5^8`

\(3^{12}=\left(3^3\right)^4=9^4\)

\(5^8=\left(5^2\right)^4=25^4\)

Vì `9 < 25` `=> 25^4 > 9^4`

`=> 3^12 > 5^8`

Vậy, `3^12 > 5^8`

`b)`

`(0,6)^9` và `(-0,9)^6`

\(\left(0,6\right)^9=\left(0,6^3\right)^3=\left(0,216\right)^3\)

\(\left(-0,9\right)^6=\left[\left(-0,9\right)^2\right]^3=\left(0,81\right)^3\)

Vì `0,81 > 0,216 => (0,81)^3 > (0,216)^3`

`=> (0,6)^9 < (-0,9)^6`

Vậy, `(0,6)^9<(-0,9)^6`

26 tháng 6 2023

1.a) Có 312 = 33.4 = 274 ;

58 = 52.4 = 254 

Dễ thấy 274 > 254 nên 312 > 58

b) Có  \(0,6^9=\dfrac{6^9}{10^9}=\dfrac{6^{3.3}}{10^9}=\dfrac{216^3}{10^9}\) 

mà \(\left(-0,9\right)^6=0,9^6=\dfrac{9^6}{10^6}=\dfrac{9^6.10^3}{10^9}=\dfrac{9^{2.3}.10^3}{10^9}=\dfrac{81^3.10^3}{10^9}=\dfrac{810^3}{10^9}\)

Dễ thấy \(\dfrac{216^3}{10^9}< \dfrac{810^3}{10^9}\Rightarrow0,6^9< \left(-0,9\right)^6\)

 

20 tháng 12 2015

CHTT nha bạn ! 

20 tháng 12 2015

câu hỏi tương tự nha bạn         ^^

14 tháng 6 2018

a) \(\frac{-7}{9}và\frac{3}{-8}\)

Ta có: \(\frac{-7}{9}=\frac{-56}{72}\)

\(\frac{3}{-8}=\frac{-3}{8}=\frac{-21}{72}\)

 \(Vì\frac{-56}{72}< \frac{-21}{72}nên\frac{-7}{9}< \frac{3}{-8}\)

b)\(\frac{209}{310}và\frac{-718}{599}\)

Ta có: \(\frac{209}{310}>0\)

\(\frac{-718}{599}< 0\)

\(Vì\frac{209}{310}>0và\frac{-718}{599}< 0nên\frac{209}{310}>\frac{-718}{599}\)

14 tháng 6 2018

Bạn bấm máy tính ấy 

31 tháng 10 2020

cần gấp

19 tháng 12 2021

^$@*&^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$%$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%$%$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$%%%%%%%%$%%$%$%$%$%%%%%%%%%%%%%%%%%%454%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%$%%%%%%%%%%%%$%$%%$$%$%$%$%$%$%$%$%$