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

Toán Lớp 8: (x-2)²-4x+1=(x+3)(x-5) giúp em vowsi maasy bồ ơi

Toán Lớp 8: (x-2)²-4x+1=(x+3)(x-5)
giúp em vowsi maasy bồ ơi

Comments ( 2 )

  1. Giải đáp:
     $(x-2)²-4x+1=(x+3).(x-5)$
    $⇔ x²-4x+4-4x+1= x²-5x+3x-15$
    $⇔ x²-8x+5= x²-2x-15$
    $⇔ x²-8x+5-x²+2x+15=0$
    $⇔ (x²-x²)+(2x-8x)+(5+15)=0$
    $⇔ -6x+20=0$
    $⇔ -6x= -20$
    $⇔ x= \dfrac{10}{3}$
    $Vậy$ $x= \dfrac{10}{3}$
     

  2. (x-2)²-4x+1=(x+3)(x-5)
    ⇔x²-4x+2²-4x+1= x²-5x+3x-15
    ⇔x²-4x+4-4x+1-x²+5x-3x+15=0
    ⇔-2x +20 =0
    ⇔-2x        = -20
    ⇔ x           = -20 : (-2) = 10
    vậy x=10
     

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