BĂNG NHAU

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

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

Vì \(72^{44}>72^{41}\Rightarrow72^{44}.71>72^{43}.71\Rightarrow72^{45}-72^{44}>72^{44}-72^{43}\)

Theo đề bài ta có:

72⁴⁵ - 72⁴⁴ = 72⁴⁴ x ( 72 - 1 ) = 72⁴⁴ x 71

72⁴⁴ - 72⁴³ = 72⁴³ x ( 72 - 1 ) = 72⁴³ x 71

Mà 72⁴⁴ > 72⁴³ ; 71 = 71

=> 72⁴⁵ - 72⁴⁴ > 72⁴⁴ - 72⁴³ 

Lê Quang Phúc tại sao lại lấy 72-1

Ta có: \(72^{45}-72^{44}=72^{44}\left(72-1\right)\)

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

=> \(72^{44}\left(72-1\right)>72^{43}\left(72-1\right)\) hay \(72^{45}-72^{44}>72^{44}-72^{43}\)

T_i_c_k nha

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

72⁴⁵ - 72⁴⁴ = 72⁴⁴ - 72⁴³

       72¹      =          72¹

Ta có:

72⁴⁵ - 72⁴⁴ = 72⁴⁴.(72 - 1) = 72⁴⁴.71

72⁴⁴ - 72⁴³ = 72⁴³.(72 - 1) = 72⁴³.71

Vì 72⁴⁴.71 > 72⁴³.71

=> 72⁴⁵ - 72⁴⁴ > 72⁴⁴ - 72⁴³

Ta có:

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

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

Vì \(72^{44}.71>72^{43}.71\) nên \(72^{45}-72^{44}>72^{44}-72^{43}\)

bằng nhau

\(72^{45}-72^{44}=72^{44}\times\left(72-1\right)=72^{44}\times71\)

\(72^{44}-72^{43}=72^{43}\times\left(72-1\right)=72^{43}\times71\)

Vì \(44>43\Rightarrow72^{44}>72^{43}\Rightarrow72^{44}\times71>72^{43}\times71\)

\(\Rightarrow72^{45}-72^{44}>72^{44}-71^{43}\)

Câu 3: 

\(2S=2+2^2+2^3+...+2^{10}\)

nên \(S=2^{10}-1\)

\(5\cdot2^8=256\cdot5=1280>1023=2^{10}-1\)

Do đó: \(S< 5\cdot2^8\)

Ta có:

72⁴⁵ - 72⁴⁴ = 72⁴⁴.(72 - 1)

72⁴⁴ - 72⁴³ = 72⁴³.(72 - 1)

Vì 72⁴⁴ > 72⁴³

=> 72⁴⁵ - 72⁴⁴ > 72⁴⁴ - 72⁴³

Ủng hộ mk nha ^_-

bằng nhau