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

Toán Lớp 8: Tìm x, biết: (3x-1)(2x+8)-(x-1)(6x-5)=0.

Toán Lớp 8: Tìm x, biết: (3x-1)(2x+8)-(x-1)(6x-5)=0.

Comments ( 2 )

  1. (3x-1).(2x+8)-(x-1).(6x-5)=0
    ->3x.2x+3x.8-1.2x-1.8-(x.6x-5.x-1.6x+1.5)=0
    ->6x^2+24x-2x-8-(6x^2-5x-6x+5)=0
    ->6x^2+24x-2x-8-6x^2+5x+6x-5=0
    ->(6x^2-6x^2)+(24x+5x+6x-2x)-(8+5)=0
    ->0+33x-13=0
    ->33x=13
    ->x=\frac{13}{33}
    Vậy x=\frac{13}{33}

  2. Giải đáp+ Lời giải và giải thích chi tiết:
    (3x-1)(2x+8) – (x-1)(6x-5) = 0 
    <=> 6x^2 + 24x – 2x – 8 – (6x^2 -5x – 6x + 5) = 0  
    <=> 6x^2 + 22x – 8 – 6x^2 + 11x – 5 = 0
    <=> (6x^2 -6x^2) +(22x +11x) – (8+5) = 0
    <=> 33x – 13 = 0
    <=> x = {13}/{33}
    Vậy: x = {13}/{33}

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