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

Toán Lớp 8: (2x + 1) . ( 3x – 2 ) + x . ( 7 – 6x ) = -21 tìm x, biết

Toán Lớp 8: (2x + 1) . ( 3x – 2 ) + x . ( 7 – 6x ) = -21
tìm x, biết

Comments ( 2 )

  1. (2x + 1).( 3x – 2 )+x.( 7 – 6x )=-21
    $\Leftrightarrow$ 6x^2-4x+3x-2+7x-6x^2=-21
    $\Leftrightarrow$ [(6x^2-6x^2)+(-4x+3x+7x)]-2=-21
    $\Leftrightarrow$ 6x-2=-21
    $\Leftrightarrow$ 6x=-21+2
    $\Leftrightarrow$ 6x=-19
    $\Leftrightarrow$ x=-19 : 6
    $\Leftrightarrow$ x=-19/6
    $\text{Vậy}$ x=-19/6
     

  2. text{#Paow}
    (2x + 1).( 3x – 2 )+x.( 7 – 6x )=-21
    6x^2-4x+3x-2+7x-6x^2==-21
    (6x^2-6x^2)+(-4x+3x+7x)-2=-21
    6x-2=-21
    6x=-21+(-2)
    6x=-19
    =>x=-19/6
     

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

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