1/ ( x^2 -3x -5 ) chia hết cho (x-3) 2/(5x+2) chia hết cho(x+1) 3/(2x^2 + 3x+2) chia hết cho (x+1)

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1. 1/ $x²-3x-5\vdots x-3$

   $→x(x-3)-5\vdots x-3$

   Do $x(x-3)\vdots x-3$

   $→-5\vdots x-3$

   $→x-3\in Ư(-5)=\{±1;±5\}$

   $→x\in \{4;2;8;-2\}$

   2/ $5x+2\vdots x+1$

   $↔5(x+1)-3\vdots x+1$

   Do $5(x+1)\vdots x+1$

   $→3\vdots x+1$

   $→x+1\in Ư(3)=\{±1;±3\}$

   $→x\in \{0;-2;2;-4\}$

   3/ $2x²+3x+2\vdots x+1$

   $→2x(x+1)+x+1+1\vdots x+1$

   $→(x+1)(2x+1)+1\vdots x+1$
   Do $(x+1)(2x+1)\vdots x+1$

   $→1\vdots x+1$

   $→x+1\in Ư(1)=\{±1\}$

   $→x\in\{0;-2\}$

    

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