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Use the substitution method to solve the system of equations. 3x + 7y = 1 y = x – 7
A. (3, –4)

B. (4, –3)

C. (2, –5)

D. (5, –2)

Respuesta :

A. (3,-4 of equations

Answer:

{x,y} = {12,5}

Step-by-step explanation:


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3x-7y=1;-x+y=-7

Solution :


{x,y} = {12,5}

 


System of Linear Equations entered :


  [1]    3x - 7y = 1

  [2]    -x + y = -7


Graphic Representation of the Equations :


   -7y + 3x = 1        y - x = -7  


 




Solve by Substitution :


// Solve equation [2] for the variable  y


 [2]    y = x - 7


// Plug this in for variable  y  in equation [1]


  [1]    3x - 7•(x -7) = 1

  [1]    -4x = -48


// Solve equation [1] for the variable  x


  [1]    4x = 48


  [1]    x = 12


// By now we know this much :


   x = 12

   y = x-7


// Use the  x  value to solve for  y


   y = (12)-7 = 5


Solution :


{x,y} = {12,5}