\input epsf
\nopagenumbers
\magnification=\magstep1

\noindent {\bf Problem statement} Here are four graphs of $y=x^2$ all
``drawn'' by a computer. All of the windows are centered on the
point $(2,4)$. Find windows which could have produced the graphs
shown, and explain your answers. Also, give one example of an approximately
``straight line'' graph which could {\it not}\/ be produced by
choosing a window centered around $(2,4)$ and looking at $y=x^2$. 

\medskip

\overfullrule=0pt

\line{
{\hfil
\hbox{\vrule\vbox{\hrule
        \hbox spread 8pt{\hfil\vbox spread 8pt{\vfil
                \vbox {\hsize=1.17in\centerline{\epsfxsize=1.15in\epsfbox{w3D1.eps}}
}%
\vfil}\hfil}
\hrule}\vrule}%
\hfil}
\hfill}

\vskip -1.285in
\line{
\hskip 1.36in
{\hfil
\hbox{\vrule\vbox{\hrule
        \hbox spread 8pt{\hfil\vbox spread 8pt{\vfil
                \vbox {\hsize=1.17in\centerline{\epsfxsize=1.15in\epsfbox{w3D2.eps}}
}%
\vfil}\hfil}
\hrule}\vrule}%
\hfil}
\hfill}

\vskip -1.285in
\line{
\hskip 2.72in
{\hfil
\hbox{\vrule\vbox{\hrule
        \hbox spread 8pt{\hfil\vbox spread 8pt{\vfil
                \vbox {\hsize=1.17in\centerline{\epsfxsize=1.15in\epsfbox{w3D3.eps}}
}%
\vfil}\hfil}
\hrule}\vrule}%
\hfil}
\hfill}

\vskip -1.285in
\line{
\hskip 4.08in
{\hfil
\hbox{\vrule\vbox{\hrule
        \hbox spread 8pt{\hfil\vbox spread 8pt{\vfil
                \vbox {\hsize=1.17in\centerline{\epsfxsize=1.15in\epsfbox{w3D4.eps}}
}%
\vfil}\hfil}
\hrule}\vrule}%
\hfil}
\hfill}

\smallskip

\line{\bf \hskip .362in 
Graph \#1 \hskip .57in
Graph \#2 \hskip .58in
Graph \#3 \hskip .58in
Graph \#4 \hfil}

\end

%w3D1.eps window x=.5..3.5 y=-1..9
%w3D2.eps window x=1.99..2.01 y=3.96..4.04
%w3D3.eps window x=1.99..2.01 y=-46..54
%w3D4.eps window x=1.9999..2.0001 y=3.999999..4.000001
%You can't get a line with negative slope!



\vfil\eject\end