Consider the following predator-prey systems of differential equations dx/dt = -x/2 + xy/2 + y, dy/dt = y(1 - y) - xy/2 + y.

a. Which equation models the prey population and which equation models the predator population?
b. How does the prey population grow if there are no predators present?
c. What happens if there are a lot of prey present?

Respuesta :

Answer:

a) Prey: [tex]\frac{dy}{dt}=y(1-y)-\frac{xy}{2+y}[/tex]

Predator: [tex]\frac{dx}{dt}=\frac{xy}{2+y}-\frac{x}{2}[/tex]

b) they grow as a function y(1-y).

c) It will grow faster and probably exponentially,

Step-by-step explanation:

a)

Prey

For prey population the rate of change is given by its own growth rate, it would be a constant times the variable, minus the rate at which it is preyed upon, usually it is represent a parameter times x and y.

So the differential equation could be:

[tex]\frac{dy}{dt}=y(1-y)-\frac{xy}{2+y}[/tex]

Predator

By the other hand, the rate of change of the predator's population depends only the rate at which the predators eat preys, minus predator's intrinsic death rate.

[tex]\frac{dx}{dt}=\frac{xy}{2+y}-\frac{x}{2}[/tex]

b)  If there are no predators present the differential equation that models prey population will be:

[tex]\frac{dy}{dt}=y(1-y)[/tex]

So they grow as a function y(1-y).

c)  In the case of the population of prey is much grader than predator, it will grow faster and exponentially, because it we assume that preys have unlimited food supply.

I hope it helps you!