Trying to solve a rather difficult differential equation

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RYANDTRAVERS
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Homework Statement


Consider a system composed of two species X and Y with fractional populations x and y, respectively, where x+y=1. The two species interact in such a way that the differential equation for x is:

\begin{equation}
\frac{dx}{dt}=xyA_{0}e^{-\alpha t}
\end{equation}

where $A_{0}$ and $\alpha$ are non-negative constants. Solve the equation by separation of variables and hence show that the solution for x(0) = $x_{0}$ is:

Photo attached- too long to write out!

2. The attempt at a solution

Again... attached. The problem that I am having is that I can't make x the subject of the equation because I end up with x/(x-1) on the left hand side.
 
Attachments
  • Handwritten notes on a printed problem sheet: differential equation dx/dt = A(t)xy with A(t) = A0 e^(-αt), a substitution y = 1 - x, and the stated solution x(t) = x0 exp(A0(1 - e^(-αt))/α) / (1 - x0 + x0 exp(A0(1 - e^(-αt))/α)); the printed exercise follows.
    IMG_2611.JPG
    53.9 KB · Views: 491
  • Handwritten separation of variables derivation for dx/dt = A0 x y e^(-alpha t) with y = 1 - x, ending with x/(x-1) = (x0/(x0-1)) e^(A0(1-e^(-alpha t))/alpha) on lined paper, photographed sideways.
    IMG_2612.JPG
    46.2 KB · Views: 484
Last edited:
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RYANDTRAVERS said:

Homework Statement


Consider a system composed of two species X and Y with fractional populations x and y, respectively, where x+y=1. The two species interact in such a way that the differential equation for x is:

\begin{equation}
\frac{dx}{dt}=xyA_{0}e^{-\alpha t}
\end{equation}

where $A_{0}$ and $\alpha$ are non-negative constants. Solve the equation by separation of variables and hence show that the solution for x(0) = $x_{0}$ is:

Photo attached- too long to write out!

2. The attempt at a solution

Again... attached. The problem that I am having is that I can't make x the subject of the equation because I end up with x/(x-1) on the left hand side.
Those sideways images are very difficult to read.

I did use the 'Windows' snipping tool to show the solution you are to verify, then pasted it into a word processor app. & rotated it.
Printed equation x(t) = [x0 exp[A0(1 - e^(-at))/a]] / [1 - x0 + x0 exp[A0(1 - e^(-at))/a]], a closed-form solution for x as a function of t.

Chet's got the rest.
 
Don't worry, I was a little tired last night doing a 5 hour practice paper. I've got it now... silly me.
 
Good.

To make x the subject either of the following forms might have helped.

##\displaystyle\ \frac{x}{x-1}=\frac{1}{1-1/x}=1+\frac{1}{x-1}\ ##