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### Messages - Shengnan Li

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1
##### MT / Re: MT problem 2
« on: December 07, 2014, 11:25:43 AM »
can we use method on handout 8 to solve this question?
if we can, what value m should we choose?

Thanks.

2
##### MAT244 Math--Lectures / fast method of solution of linear equations (Handout 8 method)
« on: December 07, 2014, 10:30:12 AM »
Handout 8 introduced a fast method of solving linear equations with constant coefficient.
The example used was of repeated roots, where Q( r)=Q`( r) = 0.
I am wondering for a question like Problem 3 in Term test 1, how can we apply this method?
I tried to apply the equation but I got a solution of particular solution totally different from the answer key.
something like (3t^2 - 5t^2 e^(-2t))/(5t-1)

Thanks.

3
##### MAT244 Math--Lectures / Re: final exam material
« on: December 06, 2014, 01:57:53 PM »
Just want to double check that we have covered:
Ch1, Ch2 (except 2.5, 2.9), Ch3 (except 3.7), Ch4, Ch7, Ch9 (up to 9.5)

And we did not cover:
Laplace transforms in 7.9

Did we cover Jordan forms in 7.8?

Thanks.

4
##### MAT244 Math--Lectures / Re: Homework 9.3 Question 16
« on: December 05, 2014, 12:05:01 PM »
while it's assigned as a question of section 9.3, are we supposed to analysis it somehow with some knowledge we learned without 9.7 information? or it's fine to omit it since we did not cover limit cycles?

5
##### MAT244 Math--Lectures / Homework 9.3 Question 16
« on: December 04, 2014, 09:26:49 PM »
For Q16 on 9.3, phase portrait shows that xy tends toward a circle. I attached the picture below.
By definition of a critical point, I only found (0,0) but I feel like the circle related to 1-x^2-y^2 behaves similar as critical point.
How should I show that in the solution? Could anyone lead me with some procedure?