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

Toán Lớp 8: tìm x ( 3x –1)^2–9x(x-3) = x+1 giúp mình vs ạ

Toán Lớp 8: tìm x
( 3x –1)^2–9x(x-3) = x+1
giúp mình vs ạ

Comments ( 2 )

  1. (3x – 1)^2 – 9x . (x – 3) = x + 1
    9x^2 – 6x + 1 – 9x^2 + 27x = x + 1
    (9x^2 – 9x^2) + (-6x + 27x) + 1 = x + 1
    21x + 1 = x + 1 
    => 21x + 1 – 1 = x + 1 – 1
    => 21x = x
    => 21x – x = x – x
    => 20x = 0
    => x = 0
    Vậy x = 0
    Gửi bạn nha

  2. (3x-1)^2-9x(x-3)=x+1
    ⇔(3x)^2-2.3x.1+1-9x^2+27x=x+1
    ⇔9x^2-6x+1-9x^2+27x=x+1
    ⇔(9x^2-9x^2)+(27x-6x)+1=x+1
    ⇔11x+1=x+1
    ⇔11x+1-x-1=0
    ⇔10x=0⇒x=0

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