\documentclass[11pt]{article}
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\usepackage{quiz}
\usepackage{alltt}
\usepackage{email}
\usepackage{hyperref}
\begin{document}
{\bf Sample Quiz 2 Problem 2 Maple Code}.
\begin{verbatim}
F:=x->r*x*(1-x/K);
G:=x->r*x*(1-x/K)-H;solve(G(x)=0,x); # Find the roots of the quadratic

# Make plot 1, sustainable harvest
de:=diff(x(t),t)=G(x(t));r:=0.8:K:=780500:H0:=K*r/4:H:=H0-5000;
a:=K/2+(1/2)*sqrt(K^2-4*H*K/r);b:=K/2-(1/2)*sqrt(K^2-4*H*K/r);
ic:=[[0,0.9*b],[0,0.94*b],[0,0.98*b],[0,b],[0,(a+b)/2],
[0,(3*a+b)/4],[0,a],[0,1.2*a],[0,1.4*a],[0,1.6*a]];

opts:=dirfield=[10,10],arrows=line,color=gray,linecolor=black,
thickness=2;
DEtools[DEplot](de,x(t),t=0..36,x=0..K,ic,opts);
de:=diff(x(t),t)=G(x(t));

# Make plot 2, extinction
r:=0.8:K:=780500:H0:=K*r/4:H:=H0+6000;
a:=K/2;b:=K/2;# Double real root values, useful for H approx H0
ic:=[[0,0.9*b],[0,0.94*b],[0,0.98*b],[0,b],[0,a],[0,1.2*a],
[0,1.4*a],[0,1.6*a],[0,1.8*a],[0,2*a]];
opts:=dirfield=[10,10],arrows=line,color=gray,linecolor=black,
thickness=2;
DEtools[DEplot](de,x(t),t=0..36,x=0..K,ic,opts);
# The solutions are all decreasing.
\end{verbatim}

\end{document}
