(54 and 55) :

54. Evaluate the following limit. lim 20 (x,y)-(0,0) x + y Select the correct choice below and, if necessary, fill in the answer box to complete your choice. OA. lim 20 (Simplify your answer.) (x,y)-(0,0) x + y O B. The limit does not exist. 55. Evaluate the following limit. 1 - cos (xy) lim (x,y)-(0,8) xy Select the correct choice below and, if necessary, fill in the answer box to complete your choice. 1 - cos (xy) O A. lim (Simplify your answer.) (x,y)-(0,8) xy O B. The limit does not exist