Comments from the TA

h8 and h9:

• For Ass8, I marked 3.4.8, 3.7.2, 3.7.104 and 3.5.101. I considered 5 points for each problem.
• For ass9, I marked 3.9.8 and 8.1.3. I considered 10 pointsfor this assignment, 4 points for 3.9.4 and 6 points for 8.1.3. For the problem 3.9.8, many students tried to find the general solution, but you just asked them to check if the given vectors were solutions. So they did the harder work.

h7:

• I marked problems 6.3.4 , 6.3.8, 6.4.1 and 3.3.104. Most students solved the Assignment 6.3.4 as follows:

  "It is the same as the previous problem (6.3.3):" and then they wrote the final answer.

  This problem is not exactly similar to 6.3.3. Their final answers are different and so you were supposed to write clearly all steps.

h6:

• For h6, I marked the following problems: 6.1.12 , 6.1.13, 6.2.6, 6.2.8.

h5:

• I marked the problems 2.5.9 , 2.5.101, 2.6.3. , 2.6.101.

h4:

• I have marked questions 2.2.105, 2.4.2, 2.5.2 and 2.5.102.

h3:

• I chose, randomly, the exercises 1.6.6, 1.7.5, 2.1.7, 2.2.7.
• There is one paper with no name, also a student has done Assignment 2 that I didn't mark.

h2:

• I marked 1.4.102, Ex 6, Ex 14, Ex 18. Marks for each problem:
      1.4.102: 5     Ex 6: 7     Ex 14: 4     Ex. 18: 4
  So the total is: 20
• It seems we can solve the Exercise 18 of Braun in two ways, depending on what we consider as "integrating factor". The solutions we have put online is f(t)=t/2 + c/t , making the equation exact after multiplying the factor. However, the equation can be also solved as a linear equation, and we can then get f(t)=t . Both solutions were considered correct.
• Note that , for example in Ex 14, \phi(t,y)=(y^2 *e^t)/2 - y*e^(2t)+c is not a solution for the given differential equation. The correct solution should be given as \phi(t,y)=(y^2 *e^t)/2 - y*e^(2t)+c =0
• Try to do the assignment by yourself. Discussions are encouraged, but after you have thought about problems by yourself. At the end, you should write the solutions by yourself alone and you need to understand them fully. I see that some people has just copied from each other. This is not gonna help you for your exam.

h1:

• I marked the problems 1.1.4 , 1.2.3 , 1.2.103 , 1.3.4.
• most people just copied the solutions from others
• 1.1.4: Most people didn't remove or didn't know how to remove |(x-1)/(1+x)| = (1-x)/(1+x). But they did it in question 1.3.4 (or maybe didn't know they had to put an absolute value in ln after integrating)
• 1.2.103. Most people tried to integrate and analyse the solution they got (which is not what you wanted; it is not correct) some people said f(x,y) is not continuous, but indeed it is not defined at (x,y)=(1,2).