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

Toán Lớp 8: Tìm x bằng phương pháp đặt nhân tử chung biết: 2x^3+3x^2+3+2x=0

Toán Lớp 8: Tìm x bằng phương pháp đặt nhân tử chung biết:
2x^3+3x^2+3+2x=0

Comments ( 2 )

  1. 2x^3+3x^2+3+2x=0
    ->(2x^3+2x)+(3x^2+3)=0
    ->2x(x^2+1)+3(x^2+1)=0
    ->(x^2+1)(2x+3)=0
    Vì x^2+1>0
    ->2x+3=0
    ->2x=-3
    ->x=-3/2
     

  2. $2x³+3x²+3+2x=0$
    $⇒(2x³+3x²)+(2x+3)=0$
    $⇒x²(2x+3)+(2x+3)=0$
    $⇒(x²+1)(2x+3)=0$
    $⇒$\(\left[ \begin{array}{l}x²+1=0\\2x+3=0\end{array} \right.\)
    $⇒$\(\left[ \begin{array}{l}x²=-1\\2x=-3\end{array} \right.\)
    $⇒$\(\left[ \begin{array}{l}x²=-1(vô lí)\\x=\frac{-3}{2}(t/m)\end{array} \right.\)
    $vậy$ $x=\frac{-3}{2}$

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