Improve Your Integration Skills with Factor Homework | Solving xy' - 4y = x4ex

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Homework Help Overview

The problem involves solving the differential equation xy' - 4y = x4ex, which is situated within the context of integration techniques and the use of integrating factors.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • Participants discuss the transformation of the equation and the use of integrating factors. There is uncertainty about expressing the left side as a derivative, and some suggest verifying the left side as the derivative of a product. Others propose trying a substitution method involving y = (x^4)u to simplify the problem.

Discussion Status

The discussion is ongoing, with participants exploring different interpretations and approaches to the problem. Some guidance has been provided regarding the use of integrating factors and the product rule, but no consensus has been reached on the next steps.

Contextual Notes

There is a noted difficulty in expressing the left side of the equation as a derivative, which is central to the discussion. The participants are also navigating the implications of using integrating factors in their attempts.

BarackObama
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Homework Statement


xy' - 4y = x4ex


Homework Equations





The Attempt at a Solution


y' - 4x-1y = x3ex
x-4y' - 4x-5y = x-1ex

I'm not sure what to do next, I can't express the LS as a derivative
 
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BarackObama said:

Homework Statement


xy' - 4y = x4ex


Homework Equations





The Attempt at a Solution


y' - 4x-1y = x3ex
x-4y' - 4x-5y = x-1ex

I'm not sure what to do next, I can't express the LS as a derivative
The whole purpose of finding an integrating factor is so that you can rewrite the left side as the derivative of something.

In this case, the left side is the derivative of x-4y, which you can easily verify.
 
So, am I to make anything out of BarackObama asking about an integrating factor?

Try letting y=(x^4)u , see if u is easier to solve for.
 
BarackObama said:

Homework Statement


xy' - 4y = x4ex


Homework Equations





The Attempt at a Solution


y' - 4x-1y = x3ex
x-4y' - 4x-5y = x-1ex

I'm not sure what to do next, I can't express the LS as a derivative
The whole point of an "integrating factor", u, is that the left side becomes (uy)'. You found x^{-4} as integrating factor so the left side must be (x^{-4}y)'.

And, in fact, by the product rule, (x^{-4}y)'= x^{-4}y'- 4x^{-5}y.
 

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