SOLUTION: Solve this simultaneous equation: {{{(3/x) - (4/y) = (1/3)}}}, {{{(2/x) - (5/y) =(1)}}}

Algebra ->  Equations -> SOLUTION: Solve this simultaneous equation: {{{(3/x) - (4/y) = (1/3)}}}, {{{(2/x) - (5/y) =(1)}}}      Log On


   



Question 1186043: Solve this simultaneous equation:
%283%2Fx%29+-+%284%2Fy%29+=+%281%2F3%29, %282%2Fx%29+-+%285%2Fy%29+=%281%29

Answer by ikleyn(52779) About Me  (Show Source):
You can put this solution on YOUR website!
.
Solve this simultaneous equations

%283%2Fx%29+-+%284%2Fy%29+=+%281%2F3%29, %282%2Fx%29+-+%285%2Fy%29+=%281%29
~~~~~~~~~~~~~~~~~~


    %283%2Fx%29+-+%284%2Fy%29 = 1%2F3    (1)

    %282%2Fx%29+-+%285%2Fy%29 = 1.    (2)


Introduce new variables  u = 1%2Fx,  v = 1%2Fy.  with these variables, the equations take the form


    3u - 4v = 1%2F3      (3)

    2u - 5v = 1.      (4)


To solve it use the Elimination method.


    6u -  8v = 2%2F3    (5)

    6u - 15v = 3      (6)

  ------------------------------- Subtract eq(5) from eq(6)

        -7v = 2 1%2F3 = 7%2F3

          v = -1%2F3.


Substitute v = -1/3  into equation (6) to get  

    6u = 3 - 5 = -2,

     u         = -2%2F6 = -1%2F3.


ANSWER.  x = 1%2Fu = 1%2F%28%28-1%2F3%29%29 = -3.   y = 1%2Fv = 1%2F%28%28-1%2F3%29%29 = -3.

Solved.

Introducing new variables is one of standard methods solving such equations.


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To see many other similar solved problems,  look into the lesson
    - Solving systems of non-linear equations by reducing to linear ones
in this site.