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222-9+11+12:2*14+14 = ? ( )

Toán Lớp 6: tìm x 2^x+7 =2^2 . 16 + 192 7+2 .(x-3)=11 102: [(2^x +13)-4]=6

Toán Lớp 6: tìm x
2^x+7 =2^2 . 16 + 192
7+2 .(x-3)=11
102: [(2^x +13)-4]=6

Comments ( 2 )

  1. 2^( x + 7) = 2^2 . 16 + 192
    2^( x + 7) = 4 . 16 + 192
    2^( x + 7) = 64 + 192
    2^(x + 7) =  256
    2^( x + 7) =  2^8
    ⇒ x + 7 = 8
    x = 8 – 7
    x = 1
    Vậy x = 1
    7 + 2( x – 3) = 11
    2( x – 3) = 11 – 7
    2( x – 3) = 4
    ( x – 3) = 4 : 2
    x – 3 = 2
    x = 2 + 3
    x = 5
    Vậy x = 5
    102 : [ ( 2^ x + 13) – 4] = 6
    [ (2^x + 13) – 4] = 102 : 6
    2^x + 13) – 4= 17
    2^x + 13 =  17 + 4
    2^x + 13 = 21
    2^x = 21 – 13
    2^x = 8
    2^x = 2^3
    ⇒ x = 3
    Vậy x = 3

  2. Giải đáp:
    a) 
    2^(x + 7) = 2^2 . 16 + 192
    ⇔ 2^(x + 7) = 4 . 16 + 192
    ⇔ 2^(x + 7) = 256
    ⇔ 2^(x + 7) = 2^8
    ⇒ x + 7 = 8
    ⇔ x = 1
    S = {1} 
    ———
    b)
    7 + 2 . (x – 3) = 11
    ⇔ 7 + 2x – 6 = 11
    ⇔ 2x = 11 + 6 – 7
    ⇔ 2x = 10
    ⇔ x = 5
    S = {5}
    ———
    c)
    102 : [(2^x + 13) – 4] = 6
    ⇔ [(2^x + 13) – 4] = 102 : 6
    ⇔ [(2^x + 13) – 4] = 17
    ⇔ 2^x + 13 = 17 + 4
    ⇔ 2^x = 17 + 4 – 13
    ⇔ 2^x = 8
    ⇔ 2^x = 2^3
    ⇒ x = 3
    S = {3}
     

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222-9+11+12:2*14+14 = ? ( )

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