(d)
The only equilibrium solution of the combined model is . Thus, is the only IC for which the solution is always constant.
![[Maple Math]](images/exam1-soln84.gif){kind=small}
. Thus,
![[Maple Math]](images/exam1-soln85.gif){kind=small}
is the only IC for which the solution is always constant.
. Thus,
is the only IC for which the solution is always constant.