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

Toán Lớp 7: 12 + 2x = 3( x – 7 ) ( x + 9 ) . ( x – 2 ) = 10

Toán Lớp 7: 12 + 2x = 3( x – 7 )
( x + 9 ) . ( x – 2 ) = 10

Comments ( 1 )

  1. Giải đáp:
     
    Lời giải và giải thích chi tiết:
     12+2x=3(x-7)
    =2x+12=3x-21
    =>2x+12-12=3x-21-12
    =>2x=3x-33
    =>x=33
    (x+9).x-2=10
    =????(????−2)+9(????−2)=10
    =????(????−2)+9(????−2)=10{\color{#c92786}{x(x-2)}}+9(x-2)=10????2−2????+9(????−2)=10
    ????2−2????+9(????−2)=10x^{2}-2x+{\color{#c92786}{9(x-2)}}=10????2−2????+9????−18=10
    ????2−2????+9????−18=10x^{2}{\color{#c92786}{-2x}}+{\color{#c92786}{9x}}-18=10????2+7????−18=10
    ????2+7????−18=10x^{2}+7x-18=10????2+7????−18−10=0
    ????=−7±161√2x=\frac{-7 \pm \sqrt{161}}{2}

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