Say a Cobb Douglas like:
$$\max_{X,Y\: s.t. X \cdot P_x+ Y \cdot P_y=I} U=X^\alpha Y^\beta$$
When it comes to maximization I would do the following way (for the fastest result):
x: $\alpha/(\alpha + \beta) = r; r*income = r_2$; $r_2$/price good = x$
Is there a similar (or really fast) method to solve for minimization problems?