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

Toán Lớp 9: Giúp mình câu này với!!!!!!! 3x^4+x^2-4=0

Toán Lớp 9: Giúp mình câu này với!!!!!!!
3x^4+x^2-4=0

Comments ( 1 )

  1. 3x^4 +x^2 -4 =0 
    <=> 3x^3(x-1) +  3x^2(x-1)  + 4x^2 -4 =0
    <=> 3x^3(x-1) +3x^2(x-1) + (2x +2)(2x-2) =0
    <=> (x-1)(3x^3 + 3x^2) + 4(x+1)(x-1) =0
    <=>  (x-1)(3x^3 + 3x^2 +4x+4) =0
    <=> (x-1)(x+1)(3x^2+4) =0
    <=> \(\left[ \begin{array}{l}x-1 =0\\x+1 =0 \\ 3x^2 +4 =0\end{array} \right.\) 
    <=> \(\left[ \begin{array}{l}x=1\\x=-1\end{array} \right.\) 
    Vậy S = {1 ; -1}

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

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