Bill Goodwine's Courses

Reading: Chapter 7

Exercises: 6.13, 6.14 and 6.16.

On problem 6.14, since we are doing A1, A2, and A9 from 6.2, do you want us to use the initial condition given in 6.3 for A2 and A9 (not A3 and A9 as it's written)? Also, is it alright if we use ode45 to determine the approximate numerical solution for problem 6.16?

rahr wrote:On problem 6.14, since we are doing A1, A2, and A9 from 6.2, do you want us to use the initial condition given in 6.3 for A2 and A9 (not A3 and A9 as it's written)? Also, is it alright if we use ode45 to determine the approximate numerical solution for problem 6.16?

Yes to both.

On 6.13, I am having a difficult time doing the method of undetermined coefficients. I was able to find the solution using diagonalization and VoP. However, despite now seeing the solution, I still have no idea how to approach it using undetermined coefficients because of how the equations are dependent and the fact that there is an eigenvalue of negative four. Can you give me a hint on how to approach the problem using this method?

rahr wrote:On 6.13, I am having a difficult time doing the method of undetermined coefficients. I was able to find the solution using diagonalization and VoP. However, despite now seeing the solution, I still have no idea how to approach it using undetermined coefficients because of how the equations are dependent and the fact that there is an eigenvalue of negative four. Can you give me a hint on how to approach the problem using this method?

You need to multiply the assumed form of the particular solution by t, or maybe t^2.

Can you post the code from class?

whawes wrote:Can you post the code from class?

I'm sorry but I'm pretty sure it was lost when I logged off. That wasn't intentional on my part. Maybe it will still be on the computer when we have class on Wednesday, but that's too late for this homework.