MATH 251 Midterm: MATH 251 PSU M251Exam 2(fa08)
Document Summary
This exam has 13 questions for a total of 100 points. In order to obtain full credit for partial credit 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. November 4, 2008: (5 points) match the sketches of phase portraits for 2x2 homogeneous linear systems x = ax with the names of their critical points at the origin. 6 saddle (a) (b) node (c) (d) (e) proper node center spiral. 2 cos t (cid:19: (5 points) match the three adjectives for the critical point (cid:18)0. 2 sin t (cid:19) + c2et(cid:18) sin t. 2 sin t (cid:19) + c2(cid:18) sin t.