Question

1/So sánh:

a) 72⁴⁵ - 72⁴⁴ và 72⁴⁴ - 72⁴³

b) 2³ⁿ và 3²ⁿ (n thuộc N*)

Answer 1

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

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

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

b) T a có: \(2^{3n}=8^n\)

              \(3^{2n}=9^n\)

              \(\Rightarrow2^{3n}< 3^{2n}\)