a) `2^{2}` . 16 ≥ `2^{x}` ≥ `4^{2}` b) `9` .`27` ≤ `3^{x}` ≤ `243`

Question

a) `2^{2}` . 16 ≥ `2^{x}` ≥ `4^{2}`
b) `9` .`27` ≤ `3^{x}` ≤ `243`

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Sapo 1 year 2020-10-22T14:29:02+00:00 2 Answers 73 views 0

Answers ( )

    0
    2020-10-22T14:30:35+00:00

    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}
    $b)$ $9$ $.$ $27$ $≤$ $3^{x}$ $≤$ $243$
    $⇒$ $3^{2}$ $.$ $3^{3}$ $≤$ $3^{x}$ $≤$ $3^{5}$
    $⇒$ $3^{5}$ $≤$ $3^{x}$ $≤$ $3^{5}$
    $⇒$ $x$ $=$ $5$
    $FbBinhne2k88$

     

    0
    2020-10-22T14:30:49+00:00

    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:

     

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Giải phương trình 1 ẩn: x + 2 - 2(x + 1) = -x . Hỏi x = ? ( )