13. Suppose that 59(2) = 3 and 9(2) = 1. Let st) = 329(3). Then f'(2) = (a) 2 (b) 4 (c) 8 (d) 8 (e) none of these 14. There are two lines that pass through the point {0, 10) and that are tangent to the curve y = 1:2 + 71' + 6 at some point P. 'What is the sum of the slopes of these two lines? (a) 14 (b) 15 (c) 16 (d) 9 (e) none of these 15. Let f(x) = |:t2 31: + 2| for all a: E R. Choose the correct statement: (a) f is dierentiable at e'iurerj,r real number t. (h) f is not di'erentiable at an}r real number 1'. (c) f is not differentiable at U. ( ( d) f is not differentiable at exactly one point. e) none of these