Question

Solve each system using the substitution method.
y= 2x
5x - y =9

Answer 1

Answer:

{y,x}={6,3}

Explanation

System of Linear Equations entered :

 [1]           y=2x

 [2]           5x-y=9

Equations Simplified or Rearranged :

  [1]    y - 2x = 0

  [2]    -y + 5x = 9

Graphic Representation of the Equations :

   -2x + y = 0        5x - y = 9  

 

Solve by Substitution :

// Solve equation [1] for the variable  y

 [1]    y = 2x

// Plug this in for variable  y  in equation [2]

  [2]    -(2x) + 5x = 9

  [2]    3x = 9

// Solve equation [2] for the variable  x

  [2]    3x = 9

  [2]    x = 3

// By now we know this much :

   y = 2x

   x = 3

// Use the  x  value to solve for  y

   y = 2(3) = 6

Solution :

{y,x} = {6,3}