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

Toán Lớp 8: Thực hiện phép tính: (x-1)^2-(5+x)(x-5)=28

Toán Lớp 8: Thực hiện phép tính: (x-1)^2-(5+x)(x-5)=28

Comments ( 2 )

  1. Answer
    (x – 1)^2 – (5 + x) . (x – 5) = 28
    => x^2 – 2x + 1 -x^2 + 25 – 28 = 0
    => (x^2 – x^2) – 2x + (1 – 28 + 25) = 0
    => -2x – 2 = 0
    => -2x = 0 + 2
    => -2x = 2
    => x = 2 : (-2)
    => x = -1
    $\text{Vậy}$ x = -1

  2. ( x – 1 )^2 – (  5 + x ) ( x – 5 ) = 28
    ⇒ x^2 – 2x + 1 – x^2 + 25 – 28 =0
    ⇒ -2x -2 =0
    ⇒ -2x =2
    ⇒ x =-1
    Vậy x =-1

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

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