Problem: Find a uniformly valid approximation to the solution of $\epsilon y'' - (x^2+1)y' - y^3 = 0$ with boundary conditions $y(0)=1, y(1)=1/2$ in the limit $\epsilon \ll 0+$. 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(x) \sim \frac{1}{\sqrt{2\arctan(x) + 1}} + \left( \frac{1}{2} - \frac{1}{\sqrt{\pi/2 + 1}} \right) e^{-2(1-x)/\epsilon} }$