Proving Linear Independence of 2nd DE Solutions

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Homework Help Overview

The problem involves proving that two linearly independent solutions, v(t) and u(t), of a second-order differential equation are such that their derivatives at t=0 are not equal. The equation is given as (6t^2-t-1)y''+t^2e^ty'-(3t^3-t-1)y=t^2e^t-3t^3+1, with initial conditions v(0)=u(0)=1.

Discussion Character

  • Exploratory, Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants discuss the use of the Wronskian to establish linear independence and question its applicability in this context. There are inquiries about the uniqueness of solutions to the differential equation and the implications of the relationship between u and v. Some participants consider the differentiation of the relationship between solutions and the conditions required for their derivatives to differ.

Discussion Status

The discussion is ongoing, with participants exploring various approaches to demonstrate the independence of the solutions. There is a focus on theorems related to uniqueness and linear independence, as well as the implications of differentiating the solutions. No consensus has been reached, but several productive lines of inquiry have been initiated.

Contextual Notes

Participants are navigating the constraints of the problem, including the specific form of the differential equation and the initial conditions provided. The discussion includes questions about the general case of linear independence and the conditions under which solutions may or may not be independent.

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Homework Statement


suppose [itex]v(t) , u(t)[/itex]are two linearly independent solution of the 2nd DE.
[itex](6t^2-t-1)y''+t^2e^ty'-(3t^3-t-1)y=t^2e^t-3t^3+1[/itex]
satisfying the condition [itex]v(0)=u(0)=1[/itex], prove that[itex]u'(0) ≠ v'(0)[/itex]


Homework Equations





The Attempt at a Solution


I've tried to use Wronskian, but it seems to fail.
 
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Welcome to PF;
If u and v are solutions to the non-homogeneous DE, then u-v is...
 
You need to use a theorem on when solutions to an ODE are unique.
 
thank you Simon, yep , u-v should be one of the general solution of the corresponding homogeneous equation. But how can I find the other one ,?

deluks ,what do you mean ? (or what theorem?

In this question,let the particular solution be x(t), then
u-x, v-x is the general solution of the corresponding homogeneous equation . Are they linearly independent ? (for general case, Are they always linearly independent ?)
 
I was thinking: if ##y_1## and ##y_2## are solutions to the corresponding homogeneous equations, then surely ##u-v=c_1y_1+c_2y_2## ... what happens if you differentiate both sides? What has to happen to make u'=v'?

This approach may not be rigorous enough for your course...

You really need to show that, according to some method for demonstrating that two solutions are independent, that they cannot have the same derivative. i.e. If u and v are independent, then they satisfy some criteria ... if their derivatives are the same they cannot satisfy those criteria.

You know what it takes to make two solutions independent right?
You must know more than one way of testing independence?
 

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