a) 7 chia hết cho x + 3 b) x + 1 chia hết cho x + 3 c) 2x – 1 chia hết cho x – 2 giúp mình với

2 bình luận về “a) 7 chia hết cho x + 3 b) x + 1 chia hết cho x + 3 c) 2x – 1 chia hết cho x – 2 giúp mình với”

1. a)7\vdotsx+3

   =>x+3\in Ư(7)

   =>x+3\in{+-1;+-7}

   =>x\in{-2;-4;4;-10}

   Vậy x\in{-10;-2;+-4}

   b)x+1\vdotsx+3

   =>x+3-2\vdotsx+3

   Mà x+3\vdotsx+3

   =>-2\vdotsx+3

   =>x+3\in Ư(-2)

   =>x+3\in {+-1;+-2}

   =>x\in{-2;-4;-1;-5}

   Vậy x\in{-1;-2;-4;-5}

   c)2x-1\vdotsx-2

   =>2x-4+3\vdotsx-2

   =>2(x-2)+3\vdotsx-2

   Mà 2.(x-2)\vdotsx-2

   =>3\vdotsx-2

   =>x-2\in Ư(3)

   =>x-2\in{+-1;+-3}

   =>x\in{3;1;5;-1}

   Vậy x\in{+-1;3;5}

    

   Trả lời
2. a) 7 \vdots x+3

   => x+3\inƯ(7)={+-1,+-7}

   => x \in {-2,-4,4,-10}

   Vậy x\in{-2,-4,4,-10}

   b) x+1 \vdots x+3

   => (x+3)-2 \vdots x+3

   Vì x+3 \vdots x+3

   => -2 \vdots x+3

   => x+3 \in Ư(-2)={+-1,+-2}

   => x \in {-2,-4,-1,-3}

   Vậy x\in{-2,-4,-1,-3}

   c) 2x-1 \vdots x – 2

   => 2(x-2)+3\vdots x-2

   Vì 2(x-2) \vdots x-2

   => 3 \vdots x-2

   => x – 2 \in Ư(3)={+-1,+-3}

   => x \in {3,1,-1,5}

   Vậy x\in{3,1,-1,5}

   Trả lời