Use the elimination method to find all solutions of the system $$\begin{array}{l} 3x^2-y^2 = 11, \\ x^2+4y^2 = 8. \\ \end{array}$$ The four solutions of the system are: $(-a,-b), (-a,b),(a,-b)$, and $(a,b)$ with positive numbers
$a=$ and $b=$ .