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

Toán Lớp 8: $x/3 – x^2/4 = 0 $ $(x^2 + 1) ( 2x+1 ) + 2x = 1$

Toán Lớp 8: $x/3 – x^2/4 = 0 $
$(x^2 + 1) ( 2x+1 ) + 2x = 1$

Comments ( 2 )

  1. x/3-x^2/4=0
    ->(4x-3x^2)/12=0
    ->4x-3x^2=0
    ->x(4-3x)=0
    ->\(\left[ \begin{array}{l}x=0\\4-3x=0\end{array} \right.\) 
    ->\(\left[ \begin{array}{l}x=0\\x=\frac{3}{4}\end{array} \right.\) 
    Vậy S={0;3/4}
    (x^2+1)(2x+1)+2x=1
    ->2x^3+x^2+2x+1+2x=1 
    ->2x^3+x^2+4x=0
    ->x(2x^2+x+4)=0
    Vì 2x^2+x+4>0
    ->x=0
    Vậy S={0}

  2. a) x/3-(x^2)/(4)=0
    ⇔(4x-3x^2)/(12)=0
    ⇔4x-3x^2=0
    ⇔x(4-3x)=0
    ⇔\(\left[ \begin{array}{l}x=0\\4-3x=0\end{array} \right.\) 
    ⇔\(\left[ \begin{array}{l}x=0\\x=\dfrac{4}{3}\end{array} \right.\) 
    Vậy S={0,4/3}
    b) (x^2+1)(2x+1)+2x=1
    ⇔2x^3+x^2+2x+1+2x=1
    ⇔2x^3+x^2+4x+1-1=0
    ⇔2x^3+x^2+4x=0
    ⇔x(2x^2+x+2)=0
    Vì 2x^2+x+2≥0∀x
    ⇒x=0
    Vậy S={0}
     

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