a).
\(2.16=2.2^4=2^5\\ 4=2^2\)
theo đề bài, ta có: \(2^5\ge2^n>2^2\Rightarrow5\ge n>2\)
vì n là số tự nhiên nên : \(n=5;4;3\)
b).
\(9.27=3^2.3^3=3^5\\ 243=3^5\)
theo đề bài, ta có: \(3^5\le3^n\le3^5\Rightarrow5\le n\le5\)
=> n=5
Giải:
a)2.16\(\ge\)2n>4
2.24\(\ge\)2n>22
25\(\ge\)2n>22
\(\Rightarrow\)5\(\ge\)n>2
\(\Rightarrow\)n\(\in\){3;4;5}
b)9.27\(\le\)3n\(\le\)243
32.33\(\le\)3n\(\le\)35
35\(\le\)3n\(\le\)35
5\(\le\)n\(\le\)5
\(\Rightarrow\)n=5
a) 2.16\(\ge\)2n>4
=>2.24\(\ge\)2n>4
=>25\(\ge\)2n>22
=>5\(\ge\)n>2
=>n\(\in\){3,4,5}
b)9.27\(\le\)3n\(\le\)243
=>32.33\(\le\)3n\(\le\)35
=>35\(\le\)3n\(\le\)35
=>5\(\le\)n\(\le\)5
=>n=5
a) 2.16 ≥ 2n > 4
= 2.24 ≥ 2n > 22
= 25 ≥ 2n > 22
Suy ra: 5 ≥ n > 2
Vậy n = 5
n = 4
n = 3
b) 9.27 ≤3n ≤243
= 32 . 33 ≤ 3n ≤ 35
= 35 ≤ 3n ≤ 35
Suy ra: 5 ≤ n ≤ 5
Vậy n = 5
