What is the derivative of x(t,a) with respect to a when t=1 and a=0?

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Homework Help Overview

The discussion revolves around the differentiation of a function defined by a differential equation, specifically x'(t) = -x(t) + atx(t)^2, with initial condition x(0) = e. The focus is on evaluating the derivative of x(t, a) with respect to a at the point where t = 1 and a = 0.

Discussion Character

  • Exploratory, Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants express confusion regarding whether x is a function of one or two variables, questioning the notation used in the problem statement. There are attempts to understand the implications of differentiating with respect to a variable that may not be part of the original function definition. Some participants share their struggles with finding a solution to the differential equation and discuss their various attempts to approach the problem.

Discussion Status

The discussion is ongoing, with participants exploring different interpretations of the problem and questioning the terminology used. Some have provided insights into the nature of the function and its variables, while others continue to seek clarity on the differentiation process and the equation itself.

Contextual Notes

There is a noted lack of clarity regarding the definition of the function x(t, a) and its relationship to the original differential equation. Participants are also reflecting on their previous knowledge of systems of differential equations, which may impact their understanding of the current problem.

mkerikss
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Homework Statement


We consider the solution to the differential equation x'(t)=-x(t)+atx(t)2, x(0)=e as a function of the variable a. Define d/da x(t,a) t=1, a=0

Homework Equations





The Attempt at a Solution



I suppose the differentiation won't be too hard, but my problem is I just don't get a solution xt,a) to the equation. I've tried splitting x'(t) into dx/dt, but that didn't work, and in desperation I've tried a number of random (ok they are not random, because I have still given it some thouht but I haven't used any special method) functions involving e, sin or cos. This is actually the part of the course that's dealing with systems of differential equation, so I've forgotten some of the stuff we learned about this type of equations about a year ago. I hope you can help!
 
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Same as my previous post :-p
I brought this up so it wouldn't get lost in the depths of the forum!
 
mkerikss said:

Homework Statement


We consider the solution to the differential equation x'(t)=-x(t)+atx(t)2, x(0)=e as a function of the variable a. Define d/da x(t,a) t=1, a=0
There are a couple of things there that are confusing.
1. Is x a function of one variable or two? In the equation above you have x(t) and x'(t), which suggests that x is a function of one variable, t. Elsewhere you have x(t, a), which suggests that x is a function of two variables.
2. Are you supposed to find the partial of x(t, a) with respect to a, evaluated at t = 1 and a = 0? The use of the word "define" is throwing me off. Usually when "define" is used, it will give the definition of the thing being defined.
mkerikss said:

Homework Equations





The Attempt at a Solution



I suppose the differentiation won't be too hard, but my problem is I just don't get a solution xt,a) to the equation. I've tried splitting x'(t) into dx/dt, but that didn't work, and in desperation I've tried a number of random (ok they are not random, because I have still given it some thouht but I haven't used any special method) functions involving e, sin or cos. This is actually the part of the course that's dealing with systems of differential equation, so I've forgotten some of the stuff we learned about this type of equations about a year ago. I hope you can help!
 
1. I asked myself the same question. My guess it that x is a 1-variable function, and x(t,a) is used because a is supposed to be a variable in the second part of the problem, even if it's not originally a variable of the function x. So they're sort of trying to make things clearer by using incorrect mathematic language or something. At least that's my take on the situation.

2. You understood correctly. I don't use this terminology in English very often, so sorry for that mistake :smile:
 

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