5x – y + z = -6 2x + 7y + 3z = 8 x + 2z = 6

Question

5x – y + z = -6
2x + 7y + 3z = 8
x + 2z = 6

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Khang Minh 4 years 2021-08-05T17:03:35+00:00 1 Answers 19 views 0

Answers ( )

  1. kimcuc
    0
    2021-08-05T17:04:57+00:00
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    Answer:

    Step-by-step explanation:

    The system of equations given are:

     

     5x – y + z = -6   ————- i

     2x + 7y + 3z = 8  ———- ii

      x + 2z = 6 —————– iii

    Let us deal with equation i and ii first since they have 3 variables x, y and z;

          5x – y + z = -6                 x 7

           2x + 7y + 3z = 8            x 1

        35x  – 7y + 7z  = -42   —-  iv

          2x  + 7y + 3z  = 8       —- v

    Add equation iv and v;

        37x + 10z  = -34 ——vi

    So, let us solve equation vi and iii:

                   x + 2z = 6 – ———- iii   x 10

                   37x + 10z  = -34  — iv  x 2

        10x + 20z   = 60         vi

         74x + 20z  = -68        vii

    Subtract vi  – vii;

          -64x  = 128

              x  = -2

    So;    put x  = -2 into iii;

               x + 2z  = 6

               -2 + 2z  = 6

                2z  = 6 + 2  = 8

               z  = 4

    Put x  = -2 and z = 4 into equation i;

      5(-2) – y + 4  =  – 6

       -10 -y  +4  = -6

           -6  – y  = -6

                 -y  = 0

                  y  = 0

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Giải phương trình 1 ẩn: x + 2 - 2(x + 1) = -x . Hỏi x = ? ( )