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Final examination course: Signals and systems giúp các bạn sinh viên có thêm tài liệu để củng cố các kiến thức, ôn tập kiểm tra, thi cuối kỳ. Đây là tài liệu bổ ích để các em ôn luyện và kiểm tra kiến thức tốt, chuẩn bị cho kì thi học kì. Mời các em và các quý thầy cô giáo bộ môn tham khảo. | TailieuVNU.com VIETNAM NATIONAL UNIVERSITY HANOI Date June 17 2016 University of Engineering and Technology FINAL EXAMINATION - ANSWERS Course Signals and Systems ELT2035 Duration 90 minutes Part 1 Multiple-choice questions For problems in this part you only have to give the letter of the correct answer A B C D . Explanations are not required. Problem 1. 1 point Which one of the systems described by the following input- output relations is a stable linear time-invariant system A. y t 2 x t sin 3 π t B. y n y n 1 2 x n x t C. y t 2 u t 1 D. y n 2 x n x n 1 Answer D Problem 2. 1 point A continuous-time linear time-invariant system is described by the following transfer function 2 s 1 H s 2 s s 2 Among the following statements about the given system which one is TRUE A. The system can be both causal and stable. B. The system can be both anti-causal and stable. C. If the system is causal then it is not stable. D. If the system is stable then it is neither causal nor anti-causal. Answer D Problem 3. 1 point Which one of the following signals is NOT an energy signal A. x t e 2 t 1 u t 1 B. x n 2 n C. x t cos π t 2 π 4 1 u t u t 10 Page 1 3 TailieuVNU.com D. x n cos π n 2 π 4 1 u n u n 10 Answer C Problem 4. Given the following discrete-time periodic signal x n e j π n 2 cos π n 3 π 4 2 sin π n 4 1 What is the fundamental period of the given signal A. T 0 6 samples B. T 0 12 samples C. T 0 18 samples D. T 0 24 samples Answer D Part 2 Exercises For problems in this part detailed explanations derivations that lead to the answer must be provided. Problem 5. 3 points Given a continuous-time causal linear time-invariant system described by the following differential equation d 2 y t dy t y t dx t 2 2 x t dt dt 2 dt a Is the given system stable or not Answer Stable because all system roots lie in the left half of the s- plane. b Determine the system impulse response. Answer 2 s 1 1 1 H s 1 j 1 j 1 j 1 j s 2 s 2 s 2 s 2 1 j 1 j t t 2 2 h t e e u t c Determine the system .
