Calculus Volume 2 · free preview

The Logistic Equation

The logistic equation models growth with a carrying capacity, its S-shaped solutions rising from an initial value toward the capacity K, separable by partial fractions and analyzed for equilibria and stability.

1. The model with capacity

The model with capacity

2. Solution by partial fractions

Solution by partial fractions

3. Analysis and applications

Analysis and applications

4. Beyond the pure logistic

Beyond the pure logistic

5. Carrying capacity effect

In the logistic equation dP/dt = kP(1 - P/K), what role does K play?

6. Logistic equilibria

The logistic equation dP/dt = kP(1 - P/K) with k positive has which equilibria, and which are stable?

7. Inflection population

At what population does the logistic curve change concavity, its growth fastest?

8. Early behavior

For an initial population P_0 much smaller than K, the logistic solution's early growth approximates what?

9. Separation decomposition

To integrate the separated logistic dP/(P(1 - P/K)) = k dt, which decomposition applies?

10. Logistic denominator

The logistic solution P(t) = K/(1 + A e^(-kt)) has A = (K - P_0)/P_0. For P_0 = K/3, what is A? Answer with a number.

11. Limit at infinity

As t approaches infinity, e^(-kt) approaches zero, so the logistic P(t) approaches what value? Answer with the single letter K.

12. Inflection time

The inflection occurs when P = K/2, at time t = ln(A)/k. As a single letter, what is A in this formula? Answer with an uppercase letter.

13. Stable equilibrium definition

An equilibrium P star of an autonomous equation is called stable when what holds?

14. Rate at capacity

At P = K the logistic rate kP(1 - P/K) equals zero. As a number, what is it? Answer with a number.

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