Hello can I have some help here please. Can you write on a sheet of paper and upload it please

1. Find and sketch the domain of the following function. a) f(x, y) = In(9-9x] - y?) 2. Prove that the following function is continuous. a) f(x, y) = x2 + 12 for (x, y) * (0,0) 0 for (x, y) = (0,0) b) f (x, y ) = vx-y In(y+x) c) f(x, y) = arocos(x+ y) xy - 2y 3. Find, if it exist, or show it does not exist. lim (x,y) >(2.0) x + y-4x+4 d) f (x, y) = In(4-x-2y)