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

Toán Lớp 8: Tìm x, biết a)3x(4/3x + 1)-4x(x-2)=10 b)4x(x-5)-(x-1)(4x-3)=5

Toán Lớp 8: Tìm x, biết
a)3x(4/3x + 1)-4x(x-2)=10
b)4x(x-5)-(x-1)(4x-3)=5

Comments ( 2 )

  1. $\\$
    a,
    3x(4/3 x + 1)-4x(x-2)=10
    <=> 4x^2 + 3x – 4x^2 + 8x=10
    <=> 11x=10
    <=>x=10/11
    Vậy x=10/11
    b,
    4x(x-5)-(x-1)(4x-3)=5
    <=>4x^2 – 20x – (4x^2-3x-4x+3)=5
    <=> 4x^2-20x – 4x^2 + 7x – 3=5
    <=> -13x = 8
    <=> x=(-8)/13
    Vậy x=(-8)/13
     

  2. Lời giải:
    a)
    3x(4/3x+1)-4x(x-2)=10
    ⇔4x^(2)+3x-4x^(2)+8x=10
    ⇔(4x^(2)-4x^2)+(3x+8x)=10
    ⇔11x=10
    ⇔x=10/11
    Vậy x=10/11
    b)
    4x(x-5)-(x-1)(4x-3)=5
    ⇔4x^(2)-20x-4x^(2)+3x+4x-3=5
    ⇔(4x^(2)-4x^2)+(-20x+3x+4x)-3=5
    ⇔-13x=8
    ⇔x=-8/13
    Vậy x=-8/13

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

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