Determine stationary points for the following functions. Determine stationary points for the following functions. Determine whether or not they correspond to local maxima, minima, or saddle-points. Clearly distinguish the first-order conditions and the second-order conditions. Please show all intermediate steps. 1. f(x, y) = (y - 5x) (2y-x2)~ 2. f ( x, y) = 2xy + 108 27 + x y 3. f (x, y) = x3 + x2y + xy2 + x2 - xy+ x+1+