a)138 .   ( − 1 0 )     <         0

b ) 627 .   ( −  3 )     <       627

c ) ( −  72 )   .  8     <       −  72

a) Ta có:

16^19=(2⁴)¹⁹=2⁷⁶                       ;             8²⁵=(2³)²⁵=2⁷⁵

Vì 76>75 nên 2⁷⁶>2⁷⁵. Vậy 16¹⁹>8²⁵

b) Ta có:

72⁴⁵-72⁴⁴=72(72⁴⁴-72⁴³)

Vậy 72⁴⁵-72⁴⁴ > 72⁴⁴-72⁴³

^{c) chịu}

a, Ta có:16^19=(2^4)^19=2^76

8^25=(2^3)^25=2^75

Vì 2^75<2^76 nên 8^75<16^19

b,Ta có:72^45-72^74=72(72^44-72^73)

=>72^45-72^44>72^44-72^43 

c,MÌNH GIẢI PHẦN NÀY SAU NHÉ!

c) \(3^{99}=3^{3.33}=27^{33}\)

VÌ \(27^{33}>11^{21}=>3^{99}>11^{21}\)

27^33>11^21 vì 27>11 và 33>21

\(72^{45}-72^{44}=72^{44}.\left(72-1\right)=72^{44}.71\)

\(72^{44}-72^{43}=72^{43}.\left(72-1\right)=72^{43}.71\)

Vì \(72^{44}>72^{43}\Rightarrow72^{45}-72^{44}>72^{44}-72^{43}\)

72^45-72^44=72^44.7-72^44=72^44.(7-1) (1)

72^44-72^43=72^43.7-72^43=72^43.(7-1) (2)

Từ (1),(2)=>72^44.(7-1)>72^43(7-1)

=>72^45-72^44>72^44-72^43

Tick nhé

\(72^{45}-72^{44}=72^{44}\left(72-1\right)=71.72^{44}\\ 72^{44}-72^{43}=72^{43}\left(72-1\right)=71.72^{43}\\ Vì:72^{44}>72^{43}\Rightarrow72^{44}.71>72^{43}.71\\ Nên:72^{45}-72^{44}>72^{44}-72^{43}\)