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

Toán Lớp 6: <2x-5>=15 mũ 2-4.5 mũ 2 3x+2-3x.3x.2 mũ 3=27

Toán Lớp 6: <2x-5>=15 mũ 2-4.5 mũ 2
3x+2-3x.3x.2 mũ 3=27

Comments ( 2 )

  1. (2x-5) = 15^{2} – 4 . 5^{2}
    $\Rightarrow$ (2x-5) = 225 – 4 . 25
    $\Rightarrow$ (2x-5) = 225 – 100
    $\Rightarrow$ 2x-5 = 125
    $\Rightarrow$ 2x = 125 + 5
    $\Rightarrow$ 2x = 130
    $\Rightarrow$ x = 130 : 2
    $\Rightarrow$ x = 65
    $\text{Vậy}$ x = 65
    ________________
    b, 3x + 2 – 3x . 2^{3} = 27
    $\Rightarrow$ 3x + 2 – 3x . 8 = 27
    $\Rightarrow$ 3x + 2 – 24x = 27
    $\Rightarrow$ 3x – 24x = 27 – 2
    $\Rightarrow$ -21x = 25
    $\Rightarrow$ x = 25 : (-21)
    $\Rightarrow$ x = 25/(-21)
    $\text{Vậy}$ x = 25/(-21)

  2. a) 2x-5=15^{2}-4.5^2
    ⇔2x-5=225-100
    ⇔2x-5=125
    ⇔2x=130
    ⇔x=65
    Vậy x=65
    b) 3x+2-3x.2^3=27
    ⇔3x-24x=27-2
    ⇔-21x=25
    ⇔x=-(25)/(21) 
    Vậy x=-(25)/(21)
     

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

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