Tìm x: x – 2x² + 1 = 0

2 bình luận về “Tìm x: x – 2x² + 1 = 0”

1. x-2x^2+1=0

   =>-2x^2+x+1=0

   =>-(x-1)(2x+1)=0

   =>\(\left[ \begin{array}{l}x-1=0\\2x+1=0\end{array} \right.\) 

   =>\(\left[ \begin{array}{l}x=1\\x=-\dfrac{1}{2}\end{array} \right.\) 

   Vậy x\in{1;-1/2}

   Trả lời
2. Ta có: x-2x^2+1=0

   => x-x^2-x^2+1=0

   => (x-x^2)-(x^2-1)=0

   => x(1-x)-(x-1)(x+1)=0

   => x(1-x)+(1-x)(x+1)=0

   => (1-x)(x+x+1)=0

   => (1-x)(2x+1)=0

   =>1-x=0

   hoặc

    => 2x+1=0

   => x=1 hoặc x=-1/2

   Vậy x∈{1;-1/2}

    

   Trả lời