Giúp mình với !!!!!!!!!!!!!!

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Giúp mình với !!!!!!!!!!!!!!
giup-minh-voi

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Kiệt Gia 1 year 2020-11-12T23:48:05+00:00 1 Answers 60 views 0

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  1. Sapo1
    0
    2020-11-12T23:49:41+00:00
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    Giải thích các bước giải:

    Ta có:

    \(\begin{array}{l}
    1,\\
    a,\\
    {\left( {x + y – 2} \right)^2} + 2.\left( {x + y – 2} \right).\left( {x – y + 2} \right) + {\left( {x – y + 2} \right)^2}\\
     = {\left[ {\left( {x + y – 2} \right) + \left( {x – y + 2} \right)} \right]^2}\\
     = {\left( {2x} \right)^2}\\
     = 4{x^2}\\
    b,\\
    \left( {x + y} \right)\left( {{x^2} – xy + {y^2}} \right) + \left( {x – y} \right)\left( {{x^2} + xy + {y^2}} \right)\\
     = \left( {{x^3} + {y^3}} \right) + \left( {{x^3} – {y^3}} \right)\\
     = 2{x^3}\\
    2,\\
    a,\\
    2{x^2} + 4xy – 4x + 4 + 4{y^2} = 0\\
     \Leftrightarrow \left( {{x^2} + 4xy + 4{y^2}} \right) + \left( {{x^2} – 4x + 4} \right) = 0\\
     \Leftrightarrow {\left( {x + 2y} \right)^2} + {\left( {x – 2} \right)^2} = 0\\
     \Leftrightarrow \left\{ \begin{array}{l}
    {\left( {x + 2y} \right)^2} = 0\\
    {\left( {x – 2} \right)^2} = 0
    \end{array} \right. \Leftrightarrow \left\{ \begin{array}{l}
    x = 2\\
    y =  – 1
    \end{array} \right.\\
    b,\\
    {x^2} + 2{y^2} – 2y + 1 – 2xy = 0\\
     \Leftrightarrow \left( {{x^2} – 2xy + {y^2}} \right) + \left( {{y^2} – 2y + 1} \right) = 0\\
     \Leftrightarrow {\left( {x – y} \right)^2} + {\left( {y – 1} \right)^2} = 0\\
     \Leftrightarrow \left\{ \begin{array}{l}
    {\left( {x – y} \right)^2} = 0\\
    {\left( {y – 1} \right)^2} = 0
    \end{array} \right. \Leftrightarrow x = y = 1
    \end{array}\)

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