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

Toán Lớp 6: đề bài:tìm số tự nhiên x biết a,3x+47=45 b,35-5(x-1)=10 c,4.2^x-3=125

Toán Lớp 6: đề bài:tìm số tự nhiên x biết
a,3x+47=45
b,35-5(x-1)=10
c,4.2^x-3=125

Comments ( 2 )

  1. a, 3x+47=45
    x=2/3 
    b, 35-5(x-1)=10
        5 x (X-1)=35-10
        5x(X-1)=25
        X-1=25:5
        X-1=5
        X=5+1
        x=6
    c, 4.2^x-3=125
       4.2^x-3=125
       4.2^x = 125 + 3
       4.2^x = 128
       2^x = 128 : 4
       2^x = 32
    => 2^x = 2^5
    => x = 5
    Vậy x = 5

  2. a) 3x + 47 = 45 
    <=> 3x = 45 – 47
    <=> 3x = – 2
    <=> x = – 2/3
    $\\$
    b) 35 – 5(x – 1) = 10
    <=> 5(x – 1) = 35 – 10
    <=> 5(x – 1) = 25
    <=> x – 1 = 25 : 5
    <=> x – 1 = 5
    <=> x = 5 + 1
    <=> x = 6
    $\\$
    c) 4 . 2^x – 3 = 125
    <=> 4 . 2^x = 125 + 3
    <=> 4 . 2^x = 128
    <=> 2^x = 128/4
    <=> 2^x = 32
    <=> 2^x = 2^5
    <=> x = 5
    $#Ling$

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