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

Toán Lớp 8: giải phương trình (3x+1) ²-36(x-5) ²=0 helpp

Toán Lớp 8: giải phương trình (3x+1) ²-36(x-5) ²=0
helpp

Comments ( 2 )

  1. (3x+1) ²-36(x-5) ²=0
    ⇔ 9x^2 +6x+1 -36(x^2-10x+25 ) =0
    ⇔ 9x^2 +6x+1 -36x^2+360x-900 =0
    9x^2 +6x+1 -36x^2+360x-900 =0
    ⇔-27x^+366x-899 =0
    ⇔ 27x^-366x+899 =0
    ⇔ (27x^2-87)(-189x+609)=0
    ⇔3x(9x-29)-21(9x-29)=0
    ⇔(3x-31)(9x-29)=0
    ⇔\(\left[ \begin{array}{l}3x-31=0\\9x-29=0\end{array} \right.\) 
    ⇔\(\left[ \begin{array}{l}x=31/3\\x=29/9\end{array} \right.\) 
    KL : x ∈ { 31/3 ; 29/9}

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