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

Toán Lớp 6: a) -17 – 2x = 5 b) (6-2x)(x+7)=0 c) [124-(20-4x^2)]:30 =4

Home/ Toán Lớp 6: a) -17 – 2x = 5 b) (6-2x)(x+7)=0 c) [124-(20-4x^2)]:30 =4

Toán Lớp 6: a) -17 – 2x = 5 b) (6-2x)(x+7)=0 c) [124-(20-4x^2)]:30 =4

Tháng Hai 3, 2023 Toán học 2 Comments 0 views

Toán Lớp 6: a) -17 – 2x = 5
b) (6-2x)(x+7)=0
c) [124-(20-4x^2)]:30 =4

Comments ( 2 )

  1. buianhtuan
    buianhtuan
    3 Tháng Hai, 2023 at 1:51 chiều
    Reply
    Answer
    a, -17 – 2x = 5
    => 2x = -17 – 5
    => 2x = -22
    => x = -22 : 2
    => x = -11
    $\text{Vậy}$ x = -11
    ______________________
    b, (6 – 2x) . (x + 7) = 0
    => $\left[\begin{matrix} 6 – 2x = 0\\ x + 7 = 0\end{matrix}\right.$
    => $\left[\begin{matrix} 2x = 6 – 0\\ x = 0 – 7\end{matrix}\right.$
    => $\left[\begin{matrix} 2x = 6\\ x = – 7\end{matrix}\right.$
    => $\left[\begin{matrix} x = 6 : 2\\ x = – 7\end{matrix}\right.$
    => $\left[\begin{matrix} x = 3\\ x = – 7\end{matrix}\right.$
    $\text{Vậy}$ x \in {3 ; -7}
    __________________________
    c, [124 – (20 – 4x^2)] : 30 = 4
    => [124 – (20 – 4x^2)] = 4 . 30
    => 124 – (20 – 4x^2) = 120
    => (20 – 4x^2) = 124 – 120
    => 20 – 4x^2 = 4
    => 4x^2 = 20 – 4
    => 4x^2 = 16
    => x^2 = 16 : 4
    => x^2 = 4
    => x^2 = (+-2)^2
    => x = +-2
    $\text{Vậy}$ x \in {2 ; -2}

  2. thanhtung
    thanhtung
    3 Tháng Hai, 2023 at 1:51 chiều
    Reply
    a)
    -17-2x=5
    2x=(-17)-5
    2x=-22
    x=(-22):2
    x=-11
    Vậy x=-11
    b)
    (6-2x).(x+7)=0
    \(\left[ \begin{array}{l}6-2x=0\\x+7=0\end{array} \right.\) 
    => \(\left[ \begin{array}{l}x=3\\x=-7\end{array} \right.\) 
    Vậy $\left \{ {{x=3} \atop {x=-7}} \right.$ 
    c)
    [124-(20-4x^2)]:30=4
    [124-(20-4x^2)]=4×30
    [124-(20-4x^2)]=120
    20-4x^2=124-120
    20-4x^2=4
    4x^2=20-4
    4x^2=16
    x^2=16:4
    x^2=4
    x^2=(±2)^2
    =>x=±2
    Vậy x∈{2; -2}
    $@Masonn$
     

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

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