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

Toán Lớp 8: giá trị của x thỏa mãn x^2-100+x(x-10)= 0 là :

Toán Lớp 8: giá trị của x thỏa mãn x^2-100+x(x-10)= 0 là :

Comments ( 2 )

  1. Answer
    x^{2} – 100 + x . (x – 10) = 0
    => x^{2} – 100 + x^{2} – 10x = 0
    => (x^{2} + x^{2}) – 10x – 100 = 0
    => 2x^{2} – 10x – 100 = 0
    => 2 . (x^{2} – 5x – 50) = 0
    => (x^{2} – 5x – 50) = 0 : 2
    => x^{2} – 5x – 50 = 0
    => x^{2} – 10x + 5x – 50 = 0
    => (x^{2} – 10x) + (5x – 50) = 0
    => x . (x – 10) + 5 . (x – 10) = 0
    => (x + 5) . (x – 10) = 0
    => $\left[\begin{matrix} x+5=0\\ x-10=0\end{matrix}\right.$
    => $\left[\begin{matrix} x=0 – 5\\ x =0 + 10\end{matrix}\right.$
    => $\left[\begin{matrix} x=- 5\\ x =10\end{matrix}\right.$
    $\text{Vậy}$ x \in {-5 ; 10}

  2. x^2-100+x(x-10) = 0
    => x^2-100+x^2-100 = 0
    => 2x^2-200 = 0
    =>2(x^2-100) = 0
    =>2(x-10)(x+10) = 0
    => x = 10
                -10
    Chúc bạn hok gud

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