\documentclass[10pt]{article} \usepackage{graphicx} % expand size \setlength{\textwidth}{6.5in} \setlength{\textheight}{9.0in} \setlength{\oddsidemargin}{0in} \setlength{\evensidemargin}{0in} \setlength{\topmargin}{0pt} \setlength{\headheight}{0pt} \setlength{\headsep}{0pt} \setlength{\footskip}{0pt} % tight itemize %\setlength{\parsep}{0pt} %\setlength{\itemsep}{0ex} \newcounter{tcount} \newenvironment{tightitem}{\begin{list} {\upshape \alph{tcount}.} { \usecounter{tcount} \setlength{\parsep}{0ex} \setlength{\itemsep}{0ex} }} {\end{list}} \begin{document} %\pagenumbering{none} <-- causes a strange error message % about a missing number and something wrong with \hfil % Apparently `none' is not an option and there is no friendly message. \pagestyle{empty} %\renewcommand{\labelenumi}{\alph{enumi}.} <-- enumerate to count in a, b, c \noindent MAC 2313 Calculus 3 \hfill {\bf Test 2} \hfill 17 Oct 2002 \vspace{ 8pt} \noindent Show {\bf ALL} work for credit; be neat; and use only {\bf ONE} side of each page of paper. Do {\bf NOT} write on this page. Calculators can be used for graphing and calculating only. Give exact answers when possible. \vspace{ 0pt} \noindent 1. Use the Chain Rule to find $\partial z/\partial u$ and $\partial z/ \partial v$ when $z = \sin(x/y), x = \ln u$ and $ y = u^2-v^2$. \vspace{ 0pt} \noindent 2. Fixing Maple errors. Each of the following produced an error or an empty graph, explain how to fix each. \begin{tightitem} \item plot3d(exp\^{}x*sin(y),x=0..1,y=0..2*Pi); \item plot3d(x\^{}2-x*y+y\^{}2,x=0..1,y=1..1); \item f=sin(x)*y\^{}2+x\^{}2*sin(y);plot3d(f,x=-1..1,y=-1..1); \item plot3d(x y,x=-1..1,y=-1..1); \item plot3d(sin(x)*sin(y),x=0..pi,y=0..pi); \end{tightitem} \vspace{ -3pt} \noindent 3. For the function $f(x,y)=x^3+xy+y^2$ \begin{tightitem} \item Compute the quadratic Taylor polynomial for $f$ at the point $(-1,2)$. \item Compute the equation of the normal line to $f$ at the point $(-1,2)$. \end{tightitem} \vspace{ -3pt} \noindent 4. The graph A is a plot of $\nabla f$, the gradient of $f$ and the graph B is a contourplot of $g$. (Light regions have higher values than dark regions.] Find the co-ordinates of all extrema of $f$ and $g$ and {\bf LABEL} them as either local minimums, local maximums or saddle points. \begin{center} \hspace{1in} \includegraphics[angle=90,scale=0.3]{afat.ps} \hfill \includegraphics[angle=90,scale=0.3]{bfat.ps} \hfill \end{center} \vspace{ -10pt} \noindent 5. Find the directional derivative of $f(x,y,z) = 3x^2y^2 + 2yz$ as you leave the point $(1,-1,0)$ heading in the direction of the point $(0,1,1)$. \vspace{ 0pt} \noindent 6. The point $P$ is on the contour graph of the function $f$ (below left) and the point $Q$ is on the surface of the graph of the function $g$ (below right). Let ${\bf u}$ be the unit vector ${\bf u} = (-{\bf i}-{\bf j})/\sqrt{2}$. \noindent Find the sign (positive, negative or zero) of $f_x(P), f_y(P), f_{xx}(P), f_{yy}(P), f_{xy}(P), g_x(Q), g_y(Q), g_{xx}(Q), f_{\bf u}(P)$ and $g_{\bf u}(Q)$. \begin{center} \hspace{1in} \includegraphics[angle=90,scale=0.3]{P.ps} \hfill \includegraphics[angle=90,scale=0.3]{Q.ps} \hfill \end{center} \vspace{ 0pt} %%%\centerline{There is more test on the back.} \begin{center} There is more test on the back. \\ \end{center} \vfill \eject %\midinsert % \vskip 1.75in % \special { psfile="/home/m1/bellenot/class/cal3/t2/tanplane.ps" % angle=90 voffset=-30 hoffset=350 hscale=30 vscale=30 } %\endinsert \begin{center} \includegraphics[angle=90,scale=0.3]{tanplane.ps} \end{center} \vspace{ 0pt} \noindent 7. Check that the point $(-1, 1, 2)$ lies on the surface $\cos(x+y) = e^{xz+2}$ and find the equation of the tangent plane to this surface at $(x,y,z)=(-1,1,2)$ \vspace{ 0pt} \noindent 8. Sketch the region of integration, reverse the order of integration and evaluate $$\int_0^1 \int_{e^x}^e {y \over \ln y} \ dy \ dx$$ \vspace{ 0pt} \noindent 9. Find critical points of the function $f(x,y)=(x+y)(x^2+y^2-2)$. Classify these local extrema by filling out a table like the one below, with a separate line for each critical point. [Hint: Use your TI-89 to check that you got the correct collection of critical points.] \vskip 4pt \moveright 0.5 in \vbox{\offinterlineskip \halign {\strut \vrule \hfill \quad $#$ \quad \hfill & \vrule \hfill \quad $#$ \quad \hfill & \vrule \hfill \quad $#$ \quad \hfill & \vrule \hfill \quad $#$ \quad \hfill & \vrule \hfill \quad # \quad \hfill & \vrule \hfill \quad # \quad \hfill \vrule \cr \noalign{\hrule} (x,y) & f_{xx} & f_{yy} & f_{xy} & big D & Classification \cr \noalign{\hrule} ? & ? & ? & ? & ? & ? \cr \noalign{\hrule} } } \vspace{ 0pt} \noindent 10. Use your TI-89 to plot the $z = 1$ contour of the function $z = g(x,y) = x^2+xy+y^2$. On the same graph, plot some contour lines for $f(x,y)=x+y$. Use Lagrange Multipliers to find the maximum and minimum {\bf VALUES} for $f(x,y)$ on the constraint $g(x,y)=1$. \end{document}