Problem: Find a uniformly valid approximation to the solution of $\epsilon y'' - x y' - (3 + x)y = 0$ with boundary conditions $y(-1) = 1, y(1) = 1$ in the limit $\epsilon \to 0^+$. Use only the variables and constants given in the problem; do not define additional constants. Place your final solution in a $\boxed{}$ LaTeX environment.
Solution: $\boxed{y = e^{-(x+1)/\epsilon} + e^{(x-1)/\epsilon}}$