Problem #2. Consider the functions ft(x, y) = x2 - 2xy +y - 1 + tx where t is a parameter. a) Sketch the level curves of ft for t = -1, t = 0 and t = 1. b) Describe the range of ft, i.e., the set Rt = {ft(x) : x E R2) for t = -1, 0, 1. c) Explain why Ro is not an open set. Problem #3. Show the following: a) The limit of h(x, y) = 3xzy2 x2+12 at the origin in R2 does not exist. xy b) The function g(x, y) = x2+26 (x, y) * (0, 0) is not continuous. 0 (x, y) = (0, 0)