25 of 25 What is f" (=), where f (x) = sin x + cos z? Show all your work. Write your final answer in simplest Item 18 radical form. Item 19 If limit notation is needed in your response, use the following example as a guide: lim (r* + 2) should be E-+1 Item 20 written as lim z + 1 (x2 + 2). Item 21 (4 points) 21 Item 22 B IY Item 23 Item 24 Item 25