Urgent: Existence and Uniqueness theorem

MT25

New member
Joined
Oct 2, 2006
Messages
1
Hi Guys,

I know that I'm going against regulations of this forum, but I don´t know where else to turn.

Two hours from now I will be picked by a ambulance because I´m going to have an operation in my heart.

Anyway I have these math problems here which have caused me some trouble. I have made a deal with a teaching assistant that he will picked my assignments up within the hour.

But I'm affried that if I don't finish them in time it will put to much strain on my heart.

Therefore I will be forever greatful if there is some kind soul who would be so kind and help solve what I have typed below.

(a)

(I use the triangle inequality in (1) and (3)?)

Let I be a open interval and f: I \rightarrow \mathbb{R}^n be a continious function.

Let || \cdot || be a given norm on \mathbb{R}^n.

Show the following:

1) If there exists a C>0 then ||x|| \leq C ||C||_1; x \in \mathbb{R}^n, ||x|| _1 = \sum _{j=1} ^n |x_j|

2) The mapping I \ni t \rightarrow ||f(t)|| \in \mathbb{R} is continious on.

3) for all t1,t2 \in \ || \int_{t_1} ^{t_2} f(t) dt|| \leq | \int_{t_1} ^{t_2} ||f(t)||dt|


(b)

Looking at the system(*) of equations,

x1' = (a-bx2)* x1
x2' = (cx1 -d)*x2

open the open Quadrant K; here a,b,c and d er positive constants.

I need to show that the system can be integrated. Which means I need to show that there exist a C^1 -function, with the properties F:U \rightarrow \mathbb{R}, where U \subseteq K is open and close in K(close means that for every point in K, is a limit point for q sequence, whos elements belongs to K). Such that gradient F \notequal 0 for alle x \in U and such that F is constant for trajectories of system.

Finally I need to conclude that every max trajectory is contained in a compact subset of K, and that the system (*) field X: R \rightarrow \mathbb{R}^2.

Sincerely Yours and God bless You all,

Maria Thomson 25

p.s. I promis that if there is some kind soul who can help, then I will NEVER ask for so much again !
 
MT25 said:
Hi Guys,

I know that I'm going against regulations of this forum, but I don´t know where else to turn.

Two hours from now I will be picked by a ambulance because I´m going to have an operation in my heart.

Anyway I have these math problems here which have caused me some trouble. I have made a deal with a teaching assistant that he will picked my assignments up within the hour.

But I'm affried that if I don't finish them in time it will put to much strain on my heart.

Therefore I will be forever greatful if there is some kind soul who would be so kind and help solve what I have typed below.

(a)

(I use the triangle inequality in (1) and (3)?)

Let I be a open interval and \(\displaystyle f: I \rightarrow \mathbb{R}^n\) be a continious function.

Let \(\displaystyle || \cdot ||\) be a given norm on \(\displaystyle \mathbb{R}^n\).

Show the following:

1) If there exists a \(\displaystyle C>0\;\ then \;\ ||x|| \leq C ||C||_1; x \in \mathbb{R}^n, ||x|| _1 = \sum _{j=1} ^n |x_j|\)

2) The mapping \(\displaystyle I \ni t \rightarrow ||f(t)|| \in \mathbb{R}\) is continious on.

3) for all \(\displaystyle t1,t2 \in \ || \int_{t_1} ^{t_2} f(t) dt|| \leq | \int_{t_1} ^{t_2} ||f(t)||dt|\)


(b)

Looking at the system(*) of equations,

\(\displaystyle x1' = (a-bx2)* x1\\
x2' = (cx1 -d)*x2\)

open the open Quadrant K; here a,b,c and d er positive constants.

I need to show that the system can be integrated. Which means I need to show that there exist a \(\displaystyle C^1 -function\), with the properties \(\displaystyle F:U \rightarrow \mathbb{R}\), where \(\displaystyle U \subseteq K\) is open and close in K(close means that for every point in K, is a limit point for q sequence, whos elements belongs to K). Such that gradient \(\displaystyle F \neq 0\) for all \(\displaystyle x \in U\) and such that F is constant for trajectories of system.

Finally I need to conclude that every max trajectory is contained in a compact subset of K, and that the system \(\displaystyle (*) \;\ field \;\ X: R \rightarrow \mathbb{R}^2\).

Sincerely Yours and God bless You all,

Maria Thomson 25

p.s. I promis that if there is some kind soul who can help, then I will NEVER ask for so much again !
 
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