a) `2^{2}` . 16 ≥ `2^{x}` ≥ `4^{2}`
b) `9` .`27` ≤ `3^{x}` ≤ `243`
a) `2^{2}` . 16 ≥ `2^{x}` ≥ `4^{2}` b) `9` .`27` ≤ `3^{x}` ≤ `243`
By Hailey
By Hailey
a) `2^{2}` . 16 ≥ `2^{x}` ≥ `4^{2}`
b) `9` .`27` ≤ `3^{x}` ≤ `243`
Đáp án:
a,`2^2 . 16 ≥ 2^x ≥ 4^2`
`=> 2^2 . 2^4 ≥ 2^x ≥ (2^2)^2`
`=> 2^6 ≥ 2^x ≥ 2^4`
`=> 4 ≤ x ≤ 6`
b, `9.27 ≤ 3^x ≤ 243`
`=> 3^2 . 3^3 ≤ 3^x ≤ 3^5`
`=> 3^5 ≤ 3^x ≤ 3^5`
`=> x = 5`
Giải thích các bước giải:
Bạn tham khảo!
$a)$ $2^{2}$ $.$ $16$ $≥$ $2^{x}$ $≥$ $4^{2}$
$⇒$ $2^{2}$ $.$ $2^{4}$ $≥$ $2^{x}$ $≥$ $(2^{2})^{2}$
$⇒$ $2^{6}$ $≥$ $2^{x}$ $≥$ $2^{4}$
$⇒$ $x$ $∈$ {4 ; 5; 6}
$b)$ $9$ $.$ $27$ $≤$ $3^{x}$ $≤$ $243$
$⇒$ $3^{2}$ $.$ $3^{3}$ $≤$ $3^{x}$ $≤$ $3^{5}$
$⇒$ $3^{5}$ $≤$ $3^{x}$ $≤$ $3^{5}$
$⇒$ $x$ $=$ $5$
$FbBinhne2k88$