# Toronto Math Forum

## MAT244--2020F => MAT244--Lectures & Home Assignments => Chapter 2 => Topic started by: RunboZhang on September 18, 2020, 02:20:45 PM

Title: LEC 0201 Question
Post by: RunboZhang on September 18, 2020, 02:20:45 PM
Hi, we just had a lecture on homogenous ODE this morning, and when I went through the slides afterwards, I have found a confusion in the slide P6(pic is also attached below). I am wondering why the domain is strictly greater than minus root two? Why can't it be smaller than minus root two? Is it because the initial condition of this question is greater than 0 so that our answer needs to be greater than 0? (But why?)
Title: Re: LEC 0201 Question
Post by: Victor Ivrii on September 18, 2020, 07:51:52 PM
We have initial condition at point $xt_0=0$, and solution blows up as $t=-\l(2)$. While we can consider solution, given by this formula as $t<-ln(2)$ it is disconnected from intial condition. Our solution blew up as $t=-\ln (2)$.
Title: Re: LEC 0201 Question
Post by: kavinkandiah on September 19, 2020, 12:43:26 PM
I'm sorry, I still don't understand why we can ignore t<-ln2 just because the initial condition is y(0)=1
Title: Re: LEC 0201 Question
Post by: RunboZhang on September 19, 2020, 02:59:05 PM