title: How to solve symbolic equation system in Python?
body: <p>I am new from MATLAB to Python. I have now problem with solve equation system in Python. For example, in Matlab</p>
  
  <pre><code>R = solve( a1*[x1; x2] == [y1;y2], ...  
             a2*[x3; x4] == [y3;y4], ...
             a3*[x5; x6] == [y5;y6], ... 
             x2 == y3, x3 == y2, ...        
             x4 == y5, x5 == y4, ... 
             [    x2 x3 x4 x5    ...   
               y1 y2 y3 y4 y5 y6]...   % unknown
            );
  y1 = simplify(R.y1);
  y10 = simplify(R.y10);
  </code></pre>
  
  <p>a1..a5 are coefficient  y1 y10 are what I need to solve and they should be symbolic expression after solve. How to do this in Python?</p>