Đề: Tìm x, y ∈ N biết a/ (x – 2) (5 -x) = 0 b/ (x – 1) (x^2 + 1) = 0 c/ (x -3) (2y + 1) = 7 d/ (2x + 1) (3y – 2) = 55

Question

Đề: Tìm x, y ∈ N biết
a/ (x – 2) (5 -x) = 0
b/ (x – 1) (x^2 + 1) = 0
c/ (x -3) (2y + 1) = 7
d/ (2x + 1) (3y – 2) = 55

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Daisy 4 tuần 2021-09-07T08:10:21+00:00 1 Answers 5 views 0

Answers ( )

    0
    2021-09-07T08:12:02+00:00

    \(\begin{array}{l}
    a)\,TH1:x – 2 = 0\,hay\,x = 0 + 2 = 2\\
    TH2:\,5 – x = 0\,hay\,x = 5 – 0 = 5\\
    b)\,TH1:\,x – 1 = 0\,\,hay\,\,x = 0 + 1 = 1\\
    TH2:\,{x^2} + 1 = 0\,\,\left( {ktm\,do\,x \in N \Rightarrow {x^2} \ge 1 \Rightarrow {x^2} + 1 \ge 2 > 0} \right)\\
    c)\,TH1:\,\left\{ \begin{array}{l}
    x – 3 = 1\\
    2y + 1 = 7
    \end{array} \right. \Leftrightarrow \left\{ \begin{array}{l}
    x = 4\\
    y = 3
    \end{array} \right.\left( {tm} \right)\\
    TH2:\,\left\{ \begin{array}{l}
    x – 3 = 7\\
    2y + 1 = 1
    \end{array} \right. \Leftrightarrow \left\{ \begin{array}{l}
    x = 10\\
    y = 0
    \end{array} \right.\left( {tm} \right)\\
    d)\,TH1:\,\left\{ \begin{array}{l}
    2x + 1 = 1\\
    3y – 2 = 55
    \end{array} \right. \Leftrightarrow \left\{ \begin{array}{l}
    x = 0\\
    y = 19
    \end{array} \right.\left( {tm} \right)\\
    TH2:\,\left\{ \begin{array}{l}
    2x + 1 = 55\\
    3y – 2 = 1
    \end{array} \right. \Leftrightarrow \left\{ \begin{array}{l}
    x = 27\\
    y = 1
    \end{array} \right.\left( {tm} \right)\\
    TH3:\,\left\{ \begin{array}{l}
    2x + 1 = 5\\
    3y – 2 = 11
    \end{array} \right. \Leftrightarrow \left\{ \begin{array}{l}
    x = 2\\
    y = \dfrac{{13}}{3}
    \end{array} \right.\left( {ktm} \right)\\
    TH4:\,\left\{ \begin{array}{l}
    2x + 1 = 11\\
    3y – 2 = 5
    \end{array} \right. \Leftrightarrow \left\{ \begin{array}{l}
    x = 5\\
    y = \dfrac{7}{3}
    \end{array} \right.\left( {ktm} \right)
    \end{array}\)

     

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