Bài 1:Tìm x biết 1,X + 3 chia hết cho X-2 2, 2X + 1 chia hết cho X-5

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Bài 1:Tìm x biết
1,X + 3 chia hết cho X-2 2, 2X + 1 chia hết cho X-5

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Eloise 2 tháng 2021-10-24T17:49:07+00:00 2 Answers 3 views 0

Answers ( )

    0
    2021-10-24T17:50:32+00:00

    1/ $x+3\vdots x-2$

    $→x-2+5\vdots x-2$

    $→5\vdots x-2$

    $→x-2\in Ư(5)=\{±1;±5\}$

    $→$ Ta có bảng

    $\begin{array}{|c|c|c|}\hline x-2&1&-1&5&-5\\\hline x&3&1&7&-3\\\hline \quad&tm&tm&tm&tm\\\hline\end{array}$

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

    $→2x-10+11\vdots x-5$

    $→2(x-5)+11\vdots x-5$

    $→11\vdots x-5$

    $→x-5\in Ư(11)=\{±1;±11\}$

    $→$ Ta có bảng

    $\begin{array}{|c|c|c|}\hline x-5&1&-1&11&-11\\\hline x&6&4&16&-6\\\hline \quad&tm&tm&tm&tm\\\hline\end{array}$

     

    0
    2021-10-24T17:50:48+00:00

    `a,`

    Có: `x+3 = x – 2 + 5`

    Vì `(x – 2) \vdots (x-2)`

    `⇔5 \vdots x – 2`

    `⇒x-2 ∈ Ư(5)={±1; ±5}`

    `⇒x ∈ {-3; 1; 3; 7}`

    `b,` 

    Có: `2x + 1 = 2x – 10 + 11`

    `=2(x-5) + 11`

    Vì `2(x-5) \vdots (x-5)`

    `⇔11 \vdots x – 5`

    `⇒x – 5 ∈ Ư(11)={±1; ±11}`

    `⇒x∈{-6; 4; 6; 16}`

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