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

Toán Lớp 8: 2x-$\sqrt{x}$ =1 Bn nào giải gúp mk vs

Toán Lớp 8: 2x-$\sqrt{x}$ =1
Bn nào giải gúp mk vs

Comments ( 2 )

  1. ĐKXĐ: x>=0
    2x-\sqrt{x}=1
    <=>2x-\sqrt{x}-1=0
    <=>2x-2\sqrt{x}+\sqrt{x}-1=0
    <=>2\sqrt{x}(\sqrt{x}-1)+(\sqrt{x}-1)=0
    <=>(2\sqrt{x}+1)(\sqrt{x}-1)=0
    <=>[(2\sqrt{x}+1=0),(\sqrt{x}-1=0):}
    <=>[(2\sqrt{x}=-1(\text{VÔ LÍ})),(\sqrt{x}=1):}
    <=>x=1(TM)
    Vậy x=1

  2. ⇒ $\sqrt{x}$ = 2x – 1 (ĐK: x ≥ $$\frac{1}{2})
    ⇒ $(\sqrt{x})$² = (2x – 1)²
    ⇒ x = 4x² – 4x +1
    ⇒ 4x² – 5x + 1 = 0
    ⇒ 4x² – 4x – x + 1 = 0
    ⇒ 4x(x – 1) – (x – 1) = 0
    ⇒ (x – 1)(4x – 1) = 0
    ⇒ x – 1 = 0                      hay                      4x – 1 = 0
    ⇒ x = 1                           hay                      x = $\frac{1}{4}$  (Không TM)
    ⇒ x =1
     

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

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