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

Toán Lớp 8: (12x-5)(4x-1)+(3x-7)(1-16x)=81 Giúp

Toán Lớp 8: (12x-5)(4x-1)+(3x-7)(1-16x)=81
Giúp

Comments ( 2 )

  1. ( 12x – 5 ) ( 4x – 1 ) + ( 3x – 7 ) ( 1 – 16x ) = 81
    ⇔ 12x . 4x + 12x . ( – 1 ) – 5 . 4x – 5 . ( – 1 ) + 3x . 1 + 3x . ( – 16x ) – 7 . 1 – 7 . ( – 16x ) = 81
    ⇔ 48x^2 – 12x – 20x + 5 + 3x – 48x^2 – 7 + 112x = 81
    ⇔ 83x – 2 = 81
    ⇔ 83x = 81 + 2
    ⇔ 83x = 83
    ⇔ x = 83 : 83
    ⇔ x = 1
    Vậy x = 1

  2. (12x-5)(4x-1)+(3x-7)(1-16x)=81
    <=>48x^2-32x+5-48x^2+115x-7=81
    <=>83x-2=81
    <=>83x=83
    <=>x=1
    Vậy phương trình có nghiệm là x=1
    #Wuang
     

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

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