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

Toán Lớp 10: Tìm tham số m sao cho phương trình 2x^2-x+m-1 có 2 nghiệm phân biệt

Toán Lớp 10: Tìm tham số m sao cho phương trình 2x^2-x+m-1 có 2 nghiệm phân biệt

Comments ( 1 )

  1. $2x^2-x+m-1$
    $⇔2x^2-x+m-1=0$
    $⇔x_{1,\:2}=\dfrac{-\left(-1\right)\pm \sqrt{\left(-1\right)^2-4.2\left(m-1\right)}}{2.2}$
    $⇔x_{1,\:2}=\dfrac{-\left(-1\right)\pm \left(-8m+9\right)^{\dfrac{1}{2}}}{2.2}$
    \(⇔\left[ \begin{array}{l}x_1=\dfrac{-\left(-1\right)+\left(-8m+9\right)^{\dfrac{1}{2}}}{2.2}\\x_2=\dfrac{-\left(-1\right)-\left(-8m+9\right)^{\dfrac{1}{2}}}{2.2}\end{array} \right.\)
    \(⇔\left[ \begin{array}{l}x=\dfrac{1+\left(-8m+9\right)^{\dfrac{1}{2}}}{4}\\x=\dfrac{1-\left(-8m+9\right)^{\dfrac{1}{2}}}{4}\end{array} \right.\) 
    $\text{Vậy pt có 2 nghiệm phân biệt là:}$
    $x=\dfrac{1+\left(-8m+9\right)^{\dfrac{1}{2}}}{4}$ $;$ $x=\dfrac{1-\left(-8m+9\right)^{\dfrac{1}{2}}}{4}$

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