Logistic growth model, differential equation

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SUMMARY

The discussion centers on solving the logistic growth model represented by the differential equation dY/dt = y(c - yb), where C and B are constants. The user attempts to find an explicit solution for y but encounters difficulties, particularly with the expression ln|[(c-yb)^b]/y|. A key correction is provided, clarifying that the equation should be (1/c)ln|y| - (1/b)(b/c)ln|c - yb| = t + K, which simplifies the process by canceling the coefficient of b.

PREREQUISITES
  • Understanding of differential equations, specifically logistic growth models.
  • Familiarity with integration techniques, including partial fraction decomposition.
  • Knowledge of logarithmic properties and their application in solving equations.
  • Basic understanding of constants in mathematical modeling.
NEXT STEPS
  • Study the derivation of solutions for logistic differential equations.
  • Learn about the application of partial fraction decomposition in integration.
  • Explore the properties of logarithms and their manipulation in algebraic expressions.
  • Investigate the implications of constants in differential equations and their solutions.
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Students and educators in mathematics, particularly those focused on differential equations and mathematical modeling in biological contexts.

Wiz14
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Homework Statement


dY/dt = y(c - yb)

C and B are constants.
Im supposed to find and explicit solution for y, but I am having trouble.

Homework Equations





The Attempt at a Solution



dY/y(c - yb) = dt
∫(1/c)dy/y + ∫(b/c)dY/c - yb = ∫dt (i used partial fraction decompositions)
(1/c)ln|y| - (b/c)ln|c - yb| = t + K (K stands for an arbitrary constant)
ln|[(c-yb)^b]/y| = -ct + K (Multiplied by negative c and then combine the natural logs on the left)

What I am having trouble with is the last expression on the LHS. I have (c-yb)^b so how am I supposed to solve for y, if i don't know b?
 
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Wiz14 said:

Homework Statement


dY/dt = y(c - yb)

C and B are constants.
Im supposed to find and explicit solution for y, but I am having trouble.

Homework Equations





The Attempt at a Solution



dY/y(c - yb) = dt
∫(1/c)dy/y + ∫(b/c)dY/c - yb = ∫dt (i used partial fraction decompositions)
(1/c)ln|y| - (b/c)ln|c - yb| = t + K (K stands for an arbitrary constant)
ln|[(c-yb)^b]/y| = -ct + K (Multiplied by negative c and then combine the natural logs on the left)

What I am having trouble with is the last expression on the LHS. I have (c-yb)^b so how am I supposed to solve for y, if i don't know b?

It's very difficult to read what you wrote (use LaTex!), but there's an error here:

(1/c)ln|y| - (b/c)ln|c - yb| = t + K

That should be: ##\displaystyle \frac{1}{c}\ln|y| - \frac{1}{b}.\frac{b}{c}\ln|c-yb| = t + K## so that coefficient of b should cancel out.
 

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