a: -91/104=-7/8=-21/24

-5/6=-20/24

=>-91/104<-5/6

b: -15/21=-5/7

-36/44=-9/11

5/7=1-2/7; 9/11=1-2/11

mà 2/7>2/11

nên 5/7<9/11

=>-15/21>-36/44

ta có: 2^91>2^90

ta thấy : 2^90= (2^3)^30= 8^30

mà 7^30<8^30

suy ra 2^91>7^30

Ta có: \(2^{91}< 2^{90}=\left(2^3\right)^{30}=8^{30}\)

Thấy: \(8^{30}>7^{30}\)

\(\Rightarrow2^{90}>7^{30}\)

Vậy: \(2^{91}>7^{30}\)

Bài 1:

a: Sửa đề: 1/3^200

1/2^300=(1/8)^100

1/3^200=(1/9)^100

mà 1/8>1/9

nên 1/2^300>1/3^200

b: 1/5^199>1/5^200=1/25^100

1/3^300=1/27^100

mà 25^100<27^100

nên 1/5^199>1/3^300

                                                         Bài giải

Ta có :

\(2^{91}=2^{90}\cdot2=\left(2^3\right)^{30}\cdot2=8^{30}\cdot2>5^{30}\)

\(\Rightarrow\text{ }2^{91}>5^{30}\)

\(21^8=\left(21^2\right)^4=441^4>54^4\)

\(\Rightarrow\text{ }54^4< 21^8\)

\(108^{50}=\left(108^2\right)^{25}=11664^{25}\)

\(73^{75}=\left(73^3\right)^{25}=389017^{25}\)

\(\text{Vì }11664^{25}< 389017^{25}\text{ }\Rightarrow\text{ }108^{50}< 73^{75}\)

                                                         Bài giải

\(2^{91}=2^{90}\cdot2=\left(2^3\right)^{30}\cdot2=8^{30}\cdot2>5^{30}\)

\(\Rightarrow\text{ }2^{91}>5^{30}\)

\(21^8=\left(21^2\right)^4=441^4>54^4\)

\(\Rightarrow\text{ }54^4< 21^8\)

\(108^{50}=\left(108^2\right)^{25}=11664^{25}\)

\(73^{75}=\left(73^3\right)^{25}=389017^{25}\)

\(\text{Vì }11664^{25}< 389017^{25}\text{ }\Rightarrow\text{ }108^{50}< 73^{75}\)

2^91=(2^13)^7=8192^7 
5^35=(5^5)^7=3125^7 
Mà 8192>3125 nên 8192^7>3125^7 
=>2^91>5^35

tick nhé bạn

Ta có

\(2^{91}>2^{90}=\left(2^5\right)^{18}=32^{18}>25^{18}=\left(5^2\right)^{18}=5^{36}>5^{35}\)

=> 2⁹¹ > 5³⁵

2⁹¹=(2¹³)⁷=8192⁷

5³⁵=(5⁵)⁷=3125⁷

Vì 8192⁷>3125⁷ nên 2⁹¹>5³⁵

2^91=(2^13)^7=8192^7 
5^35=(5^5)^7=3125^7 
Mà 8192>3125 nên 8192^7>3125^7 
=>2^91>5^35

2^91=(2^13)^7=8192^7 
5^35=(5^5)^7=3125^7 
Mà 8192>3125 nên 8192^7>3125^7 
=>2^91>5^35