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

Toán Lớp 8: 1 (3x-1)^2-(3x+2)(3x-2)=0 2 (2x+5)^2-(x-1)(x+1)-3x^2=0 (Giup em voi )

Toán Lớp 8: 1 (3x-1)^2-(3x+2)(3x-2)=0
2 (2x+5)^2-(x-1)(x+1)-3x^2=0 (Giup em voi )

Comments ( 2 )

  1. #tnvt
    (3x-1)^2-(3x+2)(3x-2)=0
    <=>(3x-1)^2-(3x)^2+2^2=0
    <=>(3x-1-3x)(3x-1+3x)=-4
    <=>-(6x-1)=-4
    <=>-6x+1=-4
    <=>-6x=-5
    <=>x=5/6
    Vậy x=5/6
    (2x+5)^2-(x-1)(x+1)-3x^2=0
    <=>4x^2+20x+25-x^2+1-3x^2=0
    <=>20=-26
    <=>x=-13/10
    Vậy x=-13/10
     

  2. 1)
    $(=) 9x^2 – 6x + 1 -(9x^2 – 4) =0$
    $(=) 9x^2 – 6x + 1 – 9x^2 + 4 =0$
    $(=) -6x=-5$
    $=) x=5/6$
    2)
    $(=) 4x^2 + 20x + 25 – (x^2 – 1) – 3x^2 = 0$
    $(=) 4x^2 + 20x + 25 – x^2 + 1 – 3x^2 = 0$
    $(=) 20x = -26$
    $=) x=-13/10$

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