Concordia University

• ENGR 391

• 10/30/21, 12:50 PM Assignment 3 - Linear Equations: Attempt review https://moodle.econcordia.com/mod/quiz/review.php?attempt=39714&cmid=1889 1/13 Dashboard / My courses / ENGR 391 (Fall 2021) / Assignments / Assignment 3 - Linear Equations Started on Monday, 11 October 2021, 704 PM State Finished Completed on Monday, 11 October 2021, 1024 PM Time taken 3 hours 20 mins Grade 16.50 out of 20.00 (83%) Feedback Well done. However make sure to understand well where you did mistakes and review the corresponding lecture topics. Question 1 Complete Not graded By checking the "yes" answer below I confirm 1. that I have neither given nor received unauthorized aid to answer the questions of this assignment. 2. I agree to follow the rules in regard of online assignments as posted in the course outline 3. I used only octave or Matlab to solve the questions (I am allowed to consult all course material and my own notes) Select one: a. Yes I agree b. No I do not agree Your answer is correct. The correct answer is: Yes I agree 10/30/21, 12:50 PM Assignment 3 - Linear Equations: Attempt review https://moodle.econcordia.com/mod/quiz/review.php?attempt=39714&cmid=1889 2/13 Question 2 Correct Mark 1.00 out of 1.00 Consider the following system : Naive Gauss elimination will transform the coefficient matrix into Select one: a. b. c. d.  ? + 4? − ? ? + ? − 6? 3? − ? − ? = = = −5 −12 4 ⎛ ⎝ ⎜ ⎜ 1.000000 0 0 4.0000 −3.0000 0 −1.0000 −5.0000 3.6667 ⎞ ⎠ ⎟ ⎟ ⎛ ⎝ ⎜ ⎜ 1.000000 0 0 4.0000 −3.0000 0 −1.0000 −5.0000 23.0000 ⎞ ⎠ ⎟ ⎟ ⎛ ⎝ ⎜ ⎜ 1.000000 0 0 4.0000 −3.0000 0 −1.0000 −5.0000 −13.4100 ⎞ ⎠ ⎟ ⎟ ⎛ ⎝ ⎜ ⎜ 1.000000 0 0 4.0000 −3.0000 0 −1.0000 −5.0000 23.6667 ⎞ ⎠ ⎟ ⎟ Your answer is correct. Reference: lecture on naive Gauss elimination in topic 3 "Systems of linear equations". The correct answer is: ⎛ ⎝ ⎜ ⎜ 1.000000 0 0 4.0000 −3.0000 0 −1.0000 −5.0000 23.6667 ⎞ ⎠ ⎟ ⎟ 10/30/21, 12:50 PM Assignment 3 - Linear Equations: Attempt review https://moodle.econcordia.com/mod/quiz/review.php?attempt=39714&cmid=1889 3/13 Question 3 Correct Mark 1.00 out of 1.00 Solve the following system of linear equations by Gauss elimination using partial pivoting The coefficient matrix of the system is transformed into an upper diagonal matrix The element in the resulting upper diagonal matrix is Select one: a. 3 b. 0.9 c. -3  d. 0 0.02?1 ?1 +3?2 +0.9?2 −3?2 +?3 +2?3 = = = 0.02 1 4 ? ?22 ? Your answer is correct. Written in tableau form: Pivoting: Gauss elimination: Pivoting: Further Gauss elimination will not change the element. Consequently the answer is The correct answer is: -3 ⎡ ⎣ ⎢ ⎢ 0.02 1 0 2 0.9 −3 0 1 2 | | | 0.02 1 4 ⎤ ⎦