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

Toán Lớp 8: Tìm x nha: `3x^3 – 6x^2 + 9x = 0` `3x^3 – 12x^2 + 12x = 0`

Home/ Toán Lớp 8: Tìm x nha: `3x^3 – 6x^2 + 9x = 0` `3x^3 – 12x^2 + 12x = 0`

Toán Lớp 8: Tìm x nha: `3x^3 – 6x^2 + 9x = 0` `3x^3 – 12x^2 + 12x = 0`

Tháng Bảy 15, 2022 Toán học 2 Comments 0 views

Toán Lớp 8: Tìm x nha: 3x^3 – 6x^2 + 9x = 0
3x^3 – 12x^2 + 12x = 0

Comments ( 2 )

  1. lanhuongthu
    lanhuongthu
    15 Tháng Bảy, 2022 at 5:56 chiều
    Reply
    3x^3-6x^2+9x=0
    <=>3x(x^2-2x+3)=0
    <=>3x(x-2x+1+2)=0
    <=>3x[(x-1)^2+2]=0
    <=> \(\left[ \begin{array}{l}3x=0\\(x-1)^2+2=0\end{array} \right.\) <=>\(\left[ \begin{array}{l}x=0\\(x-1)^2=-2(ktm)\end{array} \right.\) 
    vậy S={0}
    $\\$
    $\\$
    3x^3-12x^2+12x=0 
    <=>3x(x^2-4x+4)=0
    <=>3x(x-2)^2=0
    <=> \(\left[ \begin{array}{l}3x=0\\(x-2)^2=0\end{array} \right.\) <=>\(\left[ \begin{array}{l}x=0\\x-2=0\end{array} \right.\) <=> \(\left[ \begin{array}{l}x=0\\x=2\end{array} \right.\) 
    vậy S={0;2} 

  2. quynhthanhnhu
    quynhthanhnhu
    15 Tháng Bảy, 2022 at 5:56 chiều
    Reply
    Bạn tham khảo nhé.
    3x^3-6x^2+9x=0
    <=>3x(x^2-2x+3)=0
    <=>3x(x^2-2x+1+2)=0
    <=>3x[(x-1)^2+2]=0
    <=>[(3x=0),((x-1)^2+2=0):}
    <=>[(x=0),((x-1)^2=-2(\text{Vô lý})):}
    Vậy x=0
    $\\$
    3x^3-12x^2+12x=0
    <=>3x(x^2-4x+4)=0
    <=>3x[x^2-2.2.x+2^2]=0
    <=>3x(x-2)^2=0
    <=>[(3x=0),((x-2)^2=0):}
    <=>[(x=0),(x-2=0):}
    <=>[(x=0),(x=2):}
    Vậy x\in{0;2}
     

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

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