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

Toán Lớp 8: a) x3– 9x = 0 b) (x+5)(x -2 )

Toán Lớp 8: a) x3– 9x = 0
b) (x+5)(x -2 )

Comments ( 2 )

  1. Giải đáp+Lời giải và giải thích chi tiết:
    a)  x^3-9x=0
    ⇔x(x^2-9)=0
    ⇔x(x^2-3^2)=0
    ⇔x(x-3)(x+3)=0
    $⇔\left[\begin{matrix} x=0\\ x-3=0\\ x+3=0\end{matrix}\right.$
    $⇔\left[\begin{matrix} x=0\\ x=3\\ x=-3\end{matrix}\right.$
         Vậy x=0;  3;  -3
    b)  (x+5)(x-2)
    =x.x+x.(-2)+5.x+5.(-2)
    =x^2-2x+5x-10
    =x^2+3x-10
    $\text{#LinhSad}$

  2. a)   x^3-9x=0
    ⇔x(x^2-9)=0
    ⇔x(x^2-3^2)=0
    ⇔x(x-3)(x+3)=0
    ⇔$\left[\begin{matrix} x=0\\ x-3=0\\ x+3=0\end{matrix}\right.$
    ⇔$\left[\begin{matrix} x=0\\ x=3\\ x=-3\end{matrix}\right.$
    Vậy x=0;  3;  -3
    b)  (x+5)(x-2)
    =x.(x-2)+5.(x-2)
    =x^2-2x+5x-10
    =x^2+3x-10
    @Nobitao@

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