Question

3x + 2y = 9xy , find x and y.

Answer 1

Solve by Substitution :

// Solve equation [2] for the variable  x  
 

[2] x = y - 13

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

  [1] 3•(y -13) + 2y = -9   [1] 5y = 30

// Solve equation [1] for the variable  y  

  [1] 5y = 30    [1] y = 6 

// By now we know this much :

  x = y-13   y = 6

// Use the  y  value to solve for  x  

  x = (6)-13 = -7 

Solution :

 {x,y} = {-7,6