Question

Tìm \(n\in N\) , sao cho:

\(9\le3^n< 1000\)

Answer 1

Ta có: `3^1 = 3`

`3^2 = 9`

`3^3 = 27`

`3^4 = 81`

`3^5 = 243`

`3^6 = 729`.

`3^7 = 2187`

`=> n in {2, 3, 4, 5, 6}`.

Answer 2

`9<= 3^2;3^3;3^4;3^5;3^6<1000`

`=>n in {2;3;4;5;6}`