Question 68776
<pre>
Elimination Method
1. Add or subtract the given equations to eliminate one variable.
   y term may be eliminated, if the first equation is multiply by -7
      7(5x + y = -2)
        4x + 7y = 2
      _____________

      -35x - 7y = 14
        4x + 7y = 2
      _______________
           -31x = 16
              x = -16/31

2. Replace the value of the known variable in one of the original equations
   to find the value of the unknown variable.

        4x + 7y = 2, x = -16/31
 4(-16/31) + 7y = 2
    -64/31 + 7y = 2
             7y = 126/31
              y = 18/31

  
4. Check the solution in both original equation.
           5x + y = -2, x = -16/31, y = 18/31
5(-16/31) + 18/31 = -2
   -80/31 + 18/31 = -2
           -62/21 = -2
              -2  = -2  ----------->> True

           4x + 7y = 2, x = -16/31, y = 18/31
4(-16/31)+7(18/31) = 2
   -64/31 + 126/31 = 2
             62/31 = 2
                 2 = 2  ------------>> True

Check the graph

{{{graph (300, 300, -5, 5, -3, 7, (-5)x-2, (-4/7)x+2/7)}}}

There is a unique solution, (-16/31, 18,31) </pre>