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

Toán Lớp 8: Mn giúp mik câu này nha đề là tìm x (x-1)(x-3)-(x+2)(x+4)=25

Toán Lớp 8: Mn giúp mik câu này nha đề là tìm x
(x-1)(x-3)-(x+2)(x+4)=25

Comments ( 2 )

  1. (x-1)(x-3) – (x+2)(x+4) =25
    x^2 – 3x – x + 3 – (x^2 + 4x + 2x + 8)=25
    x^2 – 3x – x + 3 – x^2 – 4x – 2x -8=25
    (x^2 – x^2 ) + (-3x -x – 4x -2x ) + (3-8)=25
    -10x – 5=25
    => -10x = 30
    =>x = -3

  2. (x-1)(x-3)-(x+2)(x+4)=25
    <=>x^2-3x-x+3-x^2-4x-2x-8=25
    <=>-10x-5=25
    <=>-10x=30
    <=>x=-3
    Vậy x=-3

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

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