Please give full explanations.

Question 2: (Continuity)-(12 points) (a): Let f : R' -> R be given by r2 In(r; + .;) . (21,12) / (0,0) ($1, 12) = (0,0). Show that: Of is defined for all (21, r2). is not continuous at (0, 0). (b): Let f : R2 -> R be given by: f(x, y) = (x, y) # (0, 0) 0 (x, y) = (0,0). . is f continuous at (0, 0)? . Compute Lo(x, y) (if it exists). . Is = continuous at (0, 0)? [Hint: check (x, y) -> (0,0) via y = 0 and r = 0] . Is f differentiable (everywhere)