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

Toán Lớp 6: Tìm x biết: 2^x + 3.2^x+2= 27- 2^x-1

Toán Lớp 6: Tìm x biết: 2^x + 3.2^x+2= 27- 2^x-1

Comments ( 2 )

  1. Lời giải và giải thích chi tiết:
    2^x + 3 . 2^(x+2) = 27 – 2^(x-1)
    => 2^x + 3 . 2^(x+2) + 2^(x-1) = 27
    => 2^x . ( 1 + 3 . 2^2 + 2^(-1) ) = 27
    => 2^x . ( 1 + 12 + 1/2 ) = 27
    => 2^x . ( 2/2 + 24/2 + 1/2 ) = 27
    => 2^x . 27/2 = 27
    => 2^x = 27 : 27/2
    => 2^x = 2
    => 2^x = 2^1
    => x = 1
                Vậy x = 1

  2. 2^x + 3 . 2^(x+2) = 27 – 2^(x-1)
    => 2^x +3  . 2^x . 4 = 27 – 2^x . 1/2
    => 2^x + 12 . 2^x = 27  – 2^x . 1/2
    => 2^x(12 +1) =27 -2^x . 1/2
    => 2^x . 13 = 27 – 2^x . 1/2 
    => 2^x . 13 + 2^x . 1/2 = 27
    => 2^x(13+1/2) =27
    => 2^x . 27/2 =27
    => 2^x =27 : 27/2
    => 2^x = 2
    => 2^x =2^1
    =>x =1
    Vậy x =1
     

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

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