This exam has 12 questions for a total of 100 points. In order to obtain full credit for each problems, all work must be shown. Credit will not be given for an answer not supported by work. The point value for each question is in parentheses to the right of the question number. You may not use a calculator on this exam. Please turn off and put away your cell phone. July 24, 2014: (6 points) consider the seventh order linear equation y(7) + 18y(5) + 81y = 0, which has a characteristic equation r7 + 18r5 + 81r3 = r3(r2 + 9)2 = 0. What is its general solution: (6 points) determine whether each pair of functions is linearly independent or linearly depen- dent. Justify your answer. (a) (2 points) t + 1, e2t (b) (2 points) 2 sin( t), cos( t) (c) (2 points) e3t 1,