A wildlife preserve expands its fenced habitat at a time–dependent rate

MATHEMATICS · Multi-part · AP · Calculus AB · Differentiation: Composite, Implicit, and Inverse Functions · Differentiation: Composite, Implicit, and Inverse Functions

Problem

A wildlife preserve expands its fenced habitat at a time–dependent rate. The total enclosed area (in square kilometers) satisfies A(t)=π(5+0.6t)2A(t)=\pi\bigl(5+0.6t\bigr)^{2}, where tt is measured in years. The density of a certain animal species within the habitat, in animals per square kilometer, is modeled by D(A)=80e−0.02AD(A)=80e^{-0.02A}. Both AA and DD are differentiable. (a) Determine dDdt\dfrac{dD}{dt} at t=4t=4 years. Show all work and state units. (b) Explain whether dDdt\dfrac{dD}{dt} is expected to remain negative for all future times under this model, and justify your conclusion using properties of the given functions.

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