a)x^2-6x+9-y^2 b)x^2-x-6=0 c)x^2+4x+3=0 d)x^2+4x-y^2+4 giúp mk nhanh vs ak

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1. `a.`

   `x^2-6x+9-y^2`

   `=>(x-3)^2-y^2`

   `=>(x-y-3)(x+y-3)`

   `b.`

   `x^2-x-6=0`

   `=>x^2+2x-3x-6=0`

   `=>(x-3)(x+2)=0`

   `=>\left[\begin{matrix} x-3=0\\ x+2=0\end{matrix}\right`

   `=>\left[\begin{matrix} x=3\\ x=-2\end{matrix}\right`

   `c.`

   `x^2+4x+3=0`

   `=>x^2+3x+x+3=0`

   `=>(x+1)(x+3)=0`

   `=>\left[\begin{matrix} x+3=0\\ x-+1=0\end{matrix}\right`

   `=>\left[\begin{matrix} x=-3\\ x=-1\end{matrix}\right`

   `d.`

   `x^2+4x-y^2+4`

   `=>(x+2)^2-y^2`

   `=>(x-y+2)(x+y+2)`

   ( Thông cảm cho mình nhé, mình chưa hiểu latex cho lắm. )

    

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2. a) $x^2 – 6x + 9  – y^2 = (x – 3)^2 – y^2 = (x – y – 3)(x + y – 3)$

   b) $x^2 – x – 6 = 0$

       $x^2 + 2x – 3x – 6 = 0$

       $x(x +2) – 3(x+2) = 0$

        $(x-3)(x+2)= 0$

   $<=> \left[ \begin{array}{l}x-3 = 0\\x+ 2= 0\end{array} \right. <=> \left[ \begin{array}{l}x=3\\x=-2\end{array} \right. $

   c) $x^2 + 4x + 3 = 0$

      $x^2 + x + 3x + 3 = 0$

      $(x+ 1)(x+3) = 0$

   $<=> \left[ \begin{array}{l}x+3 = 0\\x+1= 0\end{array} \right. <=> \left[ \begin{array}{l}x=-3\\x=-1\end{array} \right. $

   d) $x^2 + 4x  – y^2 + 4$

    $=(x + 2)^2 – y^2$

    $=(x – y + 2))(x + y + 2)$

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