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

Toán Lớp 9: x^3-31x+228=0 giải pt này giúp mik

Toán Lớp 9: x^3-31x+228=0
giải pt này giúp mik

Comments ( 2 )

  1. x^3-31x+228=0
    sửa đề :
    x^2-31x+228=0
    ⇔(x-12)x-(x-12)19=0
    ⇔(x-12)(x-19)=0
     ⇔\(\left[ \begin{array}{l}x-12=0\\x-19=0\end{array} \right.\) 
     ⇔\(\left[ \begin{array}{l}x=12\\x=19\end{array} \right.\) 
    vậy …..

  2. \qquad x^2-31x+228=0
    <=> x^2-19x-12x+228=0
    <=> x(x-19)-12(x-19)=0
    <=> (x-19)(x-12)=0
    <=> [(x-19=0),(x-12=0):}
    <=> [(x=19),(x=12):}
    Vậy S={19;12}

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