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

Toán Lớp 9: tìm nghiệm nguyên :3x^2 -2xy +y -5x +2 = 0

Toán Lớp 9: tìm nghiệm nguyên :3x^2 -2xy +y -5x +2 = 0

Comments ( 1 )

  1. \text{Giải đáp:}
    \text{S=(x; y)={(1; 0), (0; -2)}}
    \text{Lời giải và giải thích chi tiết:}
    3x^2-2xy+y-5x+2=0
    ⇔4(3x^2-2xy+y-5x+2)=0
    ⇔12x^2-8xy+4y-20x+8=0
    ⇔(12x^2-18x+6)-(8xy-4y)-(2x-1)+1=0
    ⇔6(x-1)(2x-1)-4y(2x-1)-(2x-1)+1=0
    ⇔(2x-1)(6x-6-4y-1)=-1
    ⇔(2x-1)(6x-4y-7)=-1
    ⇔ \(\left[ \begin{array}{l}\left \{ {{2x-1=1} \atop {6x-4y-7=-1}} \right.\\\left \{ {{2x-1=-1} \atop {6x-4y-7=1}} \right.\end{array} \right.\)
    ⇔ \(\left[ \begin{array}{l}\left \{ {{2x=2} \atop {6x-4y-7=-1}} \right.\\\left \{ {{2x=0} \atop {6x-4y-7=1}} \right.\end{array} \right.\)
    ⇔ \(\left[ \begin{array}{l}\left \{ {{x=1} \atop {6·1-4y-7=-1}} \right.\\\left \{ {{x=0} \atop {6·0-4y-7=1}} \right.\end{array} \right.\)
    ⇔ \(\left[ \begin{array}{l}\left \{ {{x=1} \atop {y=0}} \right.\\\left \{ {{x=0} \atop {y=-2}} \right.\end{array} \right.\) 
    \text{Vậy nghiệm của phương trình là: S=(x; y)={(1; 0), (0; -2)} }

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