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

Toán Lớp 9: a, √x-3 = √x²-5x+6 Giúp mình vs ạ

Toán Lớp 9: a, √x-3 = √x²-5x+6
Giúp mình vs ạ

Comments ( 2 )

  1. \sqrt{x-3}=\sqrt{x^2-5x+6} (x>=3)
    ⇔x-3=x^2-5x+6
    ⇔-x^2+x+5x-3-6=0
    ⇔-x^2+6x-9=0
    ⇔-(x^2-6x+9)=0
    ⇔-(x-3)^2=0
    ⇔x-3=0
    ⇔x=3 ™
    Vậy S={3}

  2. $\#phnn$
    a)\sqrt(x-3)=\sqrt(x^2-5x+6) \text{ĐK:} x\ge3
    <=>x-3=x^2-5x+6
    <=>x-3-x^2+5x-6=0
    <=>6x-x^2-9=0
    <=>-(x^2-6x+9)=0
    <=>-(x^2-2.x.3+3^2)=0
    <=>-(x-3)^2=0
    <=>x-3=0
    <=>x=3
    \text{Vậy S={3}}

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

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