Finding the limit and a differential equation

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The discussion revolves around solving the differential equation dy/dx = y - 2y^2 with the initial condition y(0) = 0.25. The user struggles to find the solution curve f(x) and is particularly challenged by the integral of 1/(y - 2y^2). They derive a general solution of y = 1/(e^-x + 2) + C, leading to a limit of 1/2 without the constant C. However, including the constant results in a limit of 5/12, which is not among the provided answer choices, prompting questions about the dependency of the limit on the constant. The conversation emphasizes the need for careful verification of calculations and the role of the constant in determining the limit.
cokezero
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i can't seem to figure this out...

if the differential equation dy/dx= y-2y^2 has a solution curve y=f(x) contianing point (0, 0.25) , then the limit as x approaches infinity of f(x) is



a)no limit

b. 0

c. 0.25

d. 0.5

e. 2


i usually just separate the variables and find f(x) then take the limit, but i can't seem to find f(x) b/c it would require the integral of 1/(y-2y^2)
 
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cokezero said:
i usually just separate the variables and find f(x) then take the limit, but i can't seem to find f(x) b/c it would require the integral of 1/(y-2y^2)

so, integrate \frac{1}{y-2y^2}! Partial fractions will do it.
 
yeah i know...
i get the equation

y= 1/(e^-x + 2) +C
without the c value it is 1/2 for the limit
but with the c value which is -1/12 i get a limit of 5/12 which is not an answer choice...

so the question becomes, does the limit depend on the c value or not?
 
That's not the answer I get for y(x). Try checking your work again. If you still can't figure it out, post what you've done and I'll try to tell you what's wrong!
 

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