Question

A)X+Y=1
X+7Y=10

B)3x+y=13
x-2y=2

C)2x+y-4
3x-y=1
D)2x+y-5
x-y=1

Answer 1

A) X+Y=1         (-1)            multiplica por - 1 para igualar o x

   X+7Y=10

    - x - y = -1

     x + 7y = 10  

          6y = 9

            y = 9/6

           y = 3/2

 x + y = 1

x  + 3/2 = 1

x = 1 - 3/2   mmc

x = 2/2 - 3/2

x = - 1/2

S = { - 1/2 , 3/2}

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B)3x+y=13

    x-2y=2  ( - 3)

  3x + y = 13

- 3x + 6y = -6

        7y = 7

         y= 7/7 = 1

x - 2y = 2

x - 2.1 = 2

x - 2 = 2

x = 2 + 2

x = 4

S ={ 4, 1 }

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C)2x+y = 4

  3x-y = 1

  5x = 5

    x =  5/5

x = 1

2x + y = 4

2.1 + y = 4

     y = 4 - 2

    y = 2

S = { 1 , 2 }

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D)2x+y=5

     x-y=1

   3x = 6

     x = 6/3

     x = 2

  2x + y = 5

  2.2 + y = 5

         y = 5- 4

        y = 1

S = { 2 , 1 }