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

Toán Lớp 9: Giải PT: √(3x^2+5x+8)-√(3x^2+5x+1) = 1

Toán Lớp 9: Giải PT:
√(3x^2+5x+8)-√(3x^2+5x+1) = 1

Comments ( 2 )

  1. √(3x^2+5x+8)-√(3x^2+5x+1) = 1
    Gọi (3x^2+5x+8 )là a
    => √(a+7)-√(a)=1
    <=> a+7=[√(a)+1]²
    <=> 6=2√(a)
    <=>√(a)=3
    <=>a=9
    <=> 3x^2+5x+1=9 
    <=> 3x^2+5x+8 =0
    ⇔ 3x-1=0
    x+8=0
    ⇔x=1/3
    x=-8

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