Assignment Worksheet 3 Problem 1. In each part, you are given a symmetric matrix LUklbXJvd0c2Iy9JK21vZHVsZW5hbWVHNiJJLFR5cGVzZXR0aW5nR0koX3N5c2xpYkdGJzYlLUkjbWlHRiQ2JVEiQUYnLyUnaXRhbGljR1EldHJ1ZUYnLyUsbWF0aHZhcmlhbnRHUSdpdGFsaWNGJy1JI21vR0YkNi1RIi5GJy9GM1Enbm9ybWFsRicvJSZmZW5jZUdRJmZhbHNlRicvJSpzZXBhcmF0b3JHRj0vJSlzdHJldGNoeUdGPS8lKnN5bW1ldHJpY0dGPS8lKGxhcmdlb3BHRj0vJS5tb3ZhYmxlbGltaXRzR0Y9LyUnYWNjZW50R0Y9LyUnbHNwYWNlR1EmMC4wZW1GJy8lJ3JzcGFjZUdGTEY5 Find the characteristic polynomial of LUklbXJvd0c2Iy9JK21vZHVsZW5hbWVHNiJJLFR5cGVzZXR0aW5nR0koX3N5c2xpYkdGJzYkLUkjbWlHRiQ2JVEiQUYnLyUnaXRhbGljR1EldHJ1ZUYnLyUsbWF0aHZhcmlhbnRHUSdpdGFsaWNGJy9GM1Enbm9ybWFsRic= and the eigenvalues. Find a basis of each eigenspace of LUklbXJvd0c2Iy9JK21vZHVsZW5hbWVHNiJJLFR5cGVzZXR0aW5nR0koX3N5c2xpYkdGJzYmLUkjbWlHRiQ2JVEiQUYnLyUnaXRhbGljR1EldHJ1ZUYnLyUsbWF0aHZhcmlhbnRHUSdpdGFsaWNGJy1JI21vR0YkNi1RIi5GJy9GM1Enbm9ybWFsRicvJSZmZW5jZUdRJmZhbHNlRicvJSpzZXBhcmF0b3JHRj0vJSlzdHJldGNoeUdGPS8lKnN5bW1ldHJpY0dGPS8lKGxhcmdlb3BHRj0vJS5tb3ZhYmxlbGltaXRzR0Y9LyUnYWNjZW50R0Y9LyUnbHNwYWNlR1EmMC4wZW1GJy8lJ3JzcGFjZUdGTC1GNjYtUSJ+RidGOUY7Rj5GQEZCRkRGRkZIRkpGTUY5(You can use the "NullSpace" command). If necessary, use Gram-Schmidt to find an orthonormal basis of each eigenspace (You can use the "GramSchimdt" command). Find an orthogonal matrix LUklbXJvd0c2Iy9JK21vZHVsZW5hbWVHNiJJLFR5cGVzZXR0aW5nR0koX3N5c2xpYkdGJzYkLUkjbWlHRiQ2JVEiUUYnLyUnaXRhbGljR1EldHJ1ZUYnLyUsbWF0aHZhcmlhbnRHUSdpdGFsaWNGJy9GM1Enbm9ybWFsRic= so that LUklbXJvd0c2Iy9JK21vZHVsZW5hbWVHNiJJLFR5cGVzZXR0aW5nR0koX3N5c2xpYkdGJzYlLUklbXN1cEdGJDYlLUkjbWlHRiQ2JVEiUUYnLyUnaXRhbGljR1EldHJ1ZUYnLyUsbWF0aHZhcmlhbnRHUSdpdGFsaWNGJy1GIzYkLUYvNiVRIlRGJ0YyRjUvRjZRJ25vcm1hbEYnLyUxc3VwZXJzY3JpcHRzaGlmdEdRIjBGJy1GLzYlUSNBUUYnRjJGNUY9 is diagonal. Part A. A := Matrix(4, 4, {(1, 1) = 1, (1, 2) = 2/3, (1, 3) = -1/3, (1, 4) = 4/3, (2, 1) = 2/3, (2, 2) = 1/3, (2, 3) = 0, (2, 4) = -2/3, (3, 1) = -1/3, (3, 2) = 0, (3, 3) = 8/3, (3, 4) = -1/3, (4, 1) = 4/3, (4, 2) = -2/3, (4, 3) = -1/3, (4, 4) = 1}); LV9JLFR5cGVzZXR0aW5nRzYkJSpwcm90ZWN0ZWRHSShfc3lzbGliRzYiSSxtcHJpbnRzbGFzaEdGKDYkNyM+SSJBR0YoLUknUlRBQkxFR0YoNiUiKiE9Vmg4LUknTUFUUklYR0YoNiM3JjcmIiIiIyIiIyIiJCMhIiJGOiMiIiVGOjcmRjgjRjdGOiIiISMhIiNGOjcmRjtGQSMiIilGOkY7NyZGPUZCRjtGN0knTWF0cml4R0YlNyMtRkg2Iy9JJCVpZEdGKEYx Part B. A := Matrix(4, 4, {(1, 1) = 4/3, (1, 2) = 1/3, (1, 3) = 1/3, (1, 4) = 0, (2, 1) = 1/3, (2, 2) = 16/9, (2, 3) = -1/9, (2, 4) = 2/9, (3, 1) = 1/3, (3, 2) = -1/9, (3, 3) = 16/9, (3, 4) = -2/9, (4, 1) = 0, (4, 2) = 2/9, (4, 3) = -2/9, (4, 4) = 10/9}); LV9JLFR5cGVzZXR0aW5nRzYkJSpwcm90ZWN0ZWRHSShfc3lzbGliRzYiSSxtcHJpbnRzbGFzaEdGKDYkNyM+SSJBR0YoLUknUlRBQkxFR0YoNiUiKnc1dU8iLUknTUFUUklYR0YoNiM3JjcmIyIiJSIiJCMiIiJGOUY6IiIhNyZGOiMiIzsiIiojISIiRkAjIiIjRkA3JkY6RkFGPiMhIiNGQDcmRjxGQ0ZGIyIjNUZASSdNYXRyaXhHRiU3Iy1GSzYjL0kkJWlkR0YoRjE= Part C. A := Matrix(4, 4, {(1, 1) = 11/6, (1, 2) = 0, (1, 3) = 1/3, (1, 4) = -1/6, (2, 1) = 0, (2, 2) = 2, (2, 3) = 0, (2, 4) = 0, (3, 1) = 1/3, (3, 2) = 0, (3, 3) = 4/3, (3, 4) = 1/3, (4, 1) = -1/6, (4, 2) = 0, (4, 3) = 1/3, (4, 4) = 11/6}) Warning, inserted missing semicolon at end of statement LV9JLFR5cGVzZXR0aW5nRzYkJSpwcm90ZWN0ZWRHSShfc3lzbGliRzYiSSxtcHJpbnRzbGFzaEdGKDYkNyM+SSJBR0YoLUknUlRBQkxFR0YoNiUiKjNhIW84LUknTUFUUklYR0YoNiM3JjcmIyIjNiIiJyIiISMiIiIiIiQjISIiRjk3JkY6IiIjRjpGOjcmRjtGOiMiIiVGPUY7NyZGPkY6RjtGN0knTWF0cml4R0YlNyMtRkY2Iy9JJCVpZEdGKEYx Instructions: For the rest of this assignment you can use the commands "Eigenvalues" and "Eigenvectors" when you need to find eigenvalues and eigenvectors. Problem 2. In each part you are given a quadratic form in two variables. In each part, use the discriminant (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) test to determine the signs of the eigenvalues. Determine if the form is degenerate or nondegenerate. Is it postive definite, postive semi-definite, indefinite, negative semi-definite or negative definite? Check your result by computing eigenvalues. Part A. q := (14/5)*x^2-(4/5)*x*y+(11/5)*y^2; LV9JLFR5cGVzZXR0aW5nRzYkJSpwcm90ZWN0ZWRHSShfc3lzbGliRzYiSSxtcHJpbnRzbGFzaEdGKDYkNyM+SSJxR0YoLCgqJEkieEdGKCIiIyMiIzkiIiYqJkYwIiIiSSJ5R0YoRjYjISIlRjQqJEY3RjEjIiM2RjQ3I0Yu Part B. q := (8/5)*x^2-(8/5)*x*y+(2/5)*y^2; LV9JLFR5cGVzZXR0aW5nRzYkJSpwcm90ZWN0ZWRHSShfc3lzbGliRzYiSSxtcHJpbnRzbGFzaEdGKDYkNyM+SSJxR0YoLCgqJEkieEdGKCIiIyMiIikiIiYqJkYwIiIiSSJ5R0YoRjYjISIpRjQqJEY3RjEjRjFGNDcjRi4= Part C. q:= -(11/5)*x^2+(4/5)*x*y-(14/5)*y^2; LV9JLFR5cGVzZXR0aW5nRzYkJSpwcm90ZWN0ZWRHSShfc3lzbGliRzYiSSxtcHJpbnRzbGFzaEdGKDYkNyM+SSJxR0YoLCgqJEkieEdGKCIiIyMhIzYiIiYqJkYwIiIiSSJ5R0YoRjYjIiIlRjQqJEY3RjEjISM5RjQ3I0Yu Part D. q := -(29/17)*x^2+(40/17)*x*y+(46/17)*y^2; LV9JLFR5cGVzZXR0aW5nRzYkJSpwcm90ZWN0ZWRHSShfc3lzbGliRzYiSSxtcHJpbnRzbGFzaEdGKDYkNyM+SSJxR0YoLCgqJEkieEdGKCIiIyMhI0giIzwqJkYwIiIiSSJ5R0YoRjYjIiNTRjQqJEY3RjEjIiNZRjQ3I0Yu Problem 3. In each part, describe the shape of the graph of the given equation. Check that you're right by using the "implicitplot" command. (The command "completesquare" may be useful). Part A. x^2+3*x*y-5*y^2+y+x-3 =0; LywuKiRJInhHNiIiIiMiIiIqJkYlRihJInlHRiZGKCIiJCokRipGJyEiJkYqRihGJUYoISIkRigiIiE= Part B. x^2-2*x*y+3*y^2+x-2*y+5 = 0; LywuKiRJInhHNiIiIiMiIiIqJkYlRihJInlHRiZGKCEiIyokRipGJyIiJEYlRihGKkYrIiImRigiIiE= Part C. -(3/2)*x^2+3*x*y-(3/2)*y^2+y+x-1 =0; LywuKiRJInhHNiIiIiMjISIkRicqJkYlIiIiSSJ5R0YmRisiIiQqJEYsRidGKEYsRitGJUYrISIiRisiIiE= Part D. -(3/2)*x^2+9*x-23/2+3*x*y-9*y-(3/2)*y^2 =0; LywuKiRJInhHNiIiIiMjISIkRidGJSIiKiMhI0JGJyIiIiomRiVGLUkieUdGJkYtIiIkRi8hIioqJEYvRidGKCIiIQ== Problem 4. Consider the quadratic form LUklbXJvd0c2Iy9JK21vZHVsZW5hbWVHNiJJLFR5cGVzZXR0aW5nR0koX3N5c2xpYkdGJzYkLUkjbWlHRiQ2JVEicUYnLyUnaXRhbGljR1EldHJ1ZUYnLyUsbWF0aHZhcmlhbnRHUSdpdGFsaWNGJy9GM1Enbm9ybWFsRic= in 4 variables given below. Diagonalize this form, i.e., find a change of coordinates 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 where LUklbXJvd0c2Iy9JK21vZHVsZW5hbWVHNiJJLFR5cGVzZXR0aW5nR0koX3N5c2xpYkdGJzYkLUkjbWlHRiQ2JVEiUUYnLyUnaXRhbGljR1EldHJ1ZUYnLyUsbWF0aHZhcmlhbnRHUSdpdGFsaWNGJy9GM1Enbm9ybWFsRic= is an orthongonal matrix, so that the expression for LUklbXJvd0c2Iy9JK21vZHVsZW5hbWVHNiJJLFR5cGVzZXR0aW5nR0koX3N5c2xpYkdGJzYkLUkjbWlHRiQ2JVEicUYnLyUnaXRhbGljR1EldHJ1ZUYnLyUsbWF0aHZhcmlhbnRHUSdpdGFsaWNGJy9GM1Enbm9ybWFsRic= in the LUklbXJvd0c2Iy9JK21vZHVsZW5hbWVHNiJJLFR5cGVzZXR0aW5nR0koX3N5c2xpYkdGJzYkLUkjbWlHRiQ2JVEiekYnLyUnaXRhbGljR1EldHJ1ZUYnLyUsbWF0aHZhcmlhbnRHUSdpdGFsaWNGJy9GM1Enbm9ybWFsRic=-coordinates is a linear combination of squares. q := (1/6)*x[1]^2+(4/3)*x[1]*x[2]-2*x[1]*x[3]+(1/3)*x[1]*x[4]-(1/3)*x[2]^2+(4/3)*x[2]*x[4]+x[3]^2+2*x[3]*x[4]+(1/6)*x[4]^2; LV9JLFR5cGVzZXR0aW5nRzYkJSpwcm90ZWN0ZWRHSShfc3lzbGliRzYiSSxtcHJpbnRzbGFzaEdGKDYkNyM+SSJxR0YoLDQqJCZJInhHRig2IyIiIiIiIyNGMyIiJyomRjBGMyZGMTYjRjRGMyMiIiUiIiQqJkYwRjMmRjE2I0Y8RjMhIiMqJkYwRjMmRjE2I0Y7RjMjRjNGPCokRjhGNCMhIiJGPComRjhGM0ZCRjNGOiokRj5GNEYzKiZGPkYzRkJGM0Y0KiRGQkY0RjU3I0Yu Instructions and Examples. Here is an procedure to compute the hessian matrix of a function. You can use it anywhere below. Hessian := proc(f, varList) Matrix(nops(varList), nops(varList), (i,j)-> diff(f, varList[i], varList[j])); end; LV9JLFR5cGVzZXR0aW5nRzYkJSpwcm90ZWN0ZWRHSShfc3lzbGliRzYiSSxtcHJpbnRzbGFzaEdGKDYkNyM+SShIZXNzaWFuR0YoZio2JEkiZkdGKEkodmFyTGlzdEdGKEYoRihGKC1JJ01hdHJpeEdGJTYlLUklbm9wc0dGJjYjOSVGNWYqNiRJImlHRihJImpHRihGKDYkSSlvcGVyYXRvckdGKEkmYXJyb3dHRihGKC1JJWRpZmZHRiY2JVQkJlQmNiM5JCZGRUY3RihGKDYmRjBGR0YxRjhGKEYoRig3I0Yu f :='f'; LV9JLFR5cGVzZXR0aW5nRzYkJSpwcm90ZWN0ZWRHSShfc3lzbGliRzYiSSxtcHJpbnRzbGFzaEdGKDYkNyM+SSJmR0YoRi03I0Yt Hessian(f(x,y), [x,y]); LV9JLFR5cGVzZXR0aW5nRzYkJSpwcm90ZWN0ZWRHSShfc3lzbGliRzYiSSxtcHJpbnRzbGFzaEdGKDYkNyMtSSdSVEFCTEVHRig2JSIqU1AheTgtSSdNQVRSSVhHRig2IzckNyQtSSVkaWZmR0YmNiQtSSJmR0YoNiRJInhHRihJInlHRigtSSIkR0YmNiRGOyIiIy1GNjYlRjhGO0Y8NyRGQS1GNjYkRjgtRj42JEY8RkBJJ01hdHJpeEdGJTcjLUZINiMvSSQlaWRHRihGLw== Hessian(f(x,y,z), [x,y,z]); LV9JLFR5cGVzZXR0aW5nRzYkJSpwcm90ZWN0ZWRHSShfc3lzbGliRzYiSSxtcHJpbnRzbGFzaEdGKDYkNyMtSSdSVEFCTEVHRig2JSIqd1swUSItSSdNQVRSSVhHRig2IzclNyUtSSVkaWZmR0YmNiQtSSJmR0YoNiVJInhHRihJInlHRihJInpHRigtSSIkR0YmNiRGOyIiIy1GNjYlRjhGO0Y8LUY2NiVGOEY7Rj03JUZCLUY2NiRGOC1GPzYkRjxGQS1GNjYlRjhGPEY9NyVGREZLLUY2NiRGOC1GPzYkRj1GQUknTWF0cml4R0YlNyMtRlI2Iy9JJCVpZEdGKEYv Hessian(x^2*y*z+z^3+y*x*z^2, [x,y,z]); LV9JLFR5cGVzZXR0aW5nRzYkJSpwcm90ZWN0ZWRHSShfc3lzbGliRzYiSSxtcHJpbnRzbGFzaEdGKDYkNyMtSSdSVEFCTEVHRig2JSIqW107USItSSdNQVRSSVhHRig2IzclNyUsJComSSJ5R0YoIiIiSSJ6R0YoRjgiIiMsJiomSSJ4R0YoRjhGOUY4RjoqJEY5RjpGOCwmKiZGPUY4RjdGOEY6RjZGOjclRjsiIiEsJiokRj1GOkY4RjxGOjclRj9GQywmRjkiIidGQEY6SSdNYXRyaXhHRiU3Iy1GSDYjL0kkJWlkR0YoRi8= A nice maple command to find the solutions of a system of polynomial equations is the command "Isolate". For example, let's find the critical points of the following function. f := x^2*y+y^2+x^3+x^2-y^3-2*x+5*y; LV9JLFR5cGVzZXR0aW5nRzYkJSpwcm90ZWN0ZWRHSShfc3lzbGliRzYiSSxtcHJpbnRzbGFzaEdGKDYkNyM+SSJmR0YoLDAqJkkieEdGKCIiI0kieUdGKCIiIkYzKiRGMkYxRjMqJEYwIiIkRjMqJEYwRjFGMyokRjJGNiEiIkYwISIjRjIiIiY3I0Yu fx := diff(f,x); LV9JLFR5cGVzZXR0aW5nRzYkJSpwcm90ZWN0ZWRHSShfc3lzbGliRzYiSSxtcHJpbnRzbGFzaEdGKDYkNyM+SSNmeEdGKCwqKiZJInhHRigiIiJJInlHRihGMSIiIyokRjBGMyIiJEYwRjMhIiNGMTcjRi4= fy := diff(f,y); LV9JLFR5cGVzZXR0aW5nRzYkJSpwcm90ZWN0ZWRHSShfc3lzbGliRzYiSSxtcHJpbnRzbGFzaEdGKDYkNyM+SSNmeUdGKCwqKiRJInhHRigiIiMiIiJJInlHRihGMSokRjNGMSEiJCIiJkYyNyNGLg== solve({fx=0, fy=0}, {x,y}); PCQvSSJ5RzYiLCoqJC1JJ1Jvb3RPZkc2JCUqcHJvdGVjdGVkR0koX3N5c2xpYkdGJTYjLCwqJEkjX1pHRioiIiUiI0IqJEYwIiIkIiNbKiRGMCIiIyEjT0YwISNLIiM3IiIiRjchIiUjIiImRjRGOyokRihGNCMhI0JGOkYoI0Y0RjcvSSJ4R0YlRig= Not so nice. Try "Isolate" to get numerical approximations. with(RootFinding): critpoints := Isolate({fx,fy}, [x,y]); LV9JLFR5cGVzZXR0aW5nRzYkJSpwcm90ZWN0ZWRHSShfc3lzbGliRzYiSSxtcHJpbnRzbGFzaEdGKDYkNyM+SStjcml0cG9pbnRzR0YoNyY3JC9JInhHRigkIisrPyMpZSUpISM1L0kieUdGKCQhKyFmRG0zIiEiKjckL0YxJCEraHU2OnpGNC9GNiQhKzV2OHc1Rjk3JC9GMSQiK3J2IipwSkY0L0Y2JCIrRiZvIno7Rjk3JC9GMSQhK0woPSRlQ0Y5L0Y2JCIrQWdwIUcjRjk3I0Yu Let's check the first one. subs(critpoints[1], fx); JCIiIUYj subs(critpoints[1], fy); JCEiJCEiKg== Pretty close. We could tell maple to use more accuracy if we needed it. Let's evaluate the hessian at the first critical point. H := Hessian(f, [x,y]); LV9JLFR5cGVzZXR0aW5nRzYkJSpwcm90ZWN0ZWRHSShfc3lzbGliRzYiSSxtcHJpbnRzbGFzaEdGKDYkNyM+SSJIR0YoLUknUlRBQkxFR0YoNiUiKnN2aE0iLUknTUFUUklYR0YoNiM3JDckLChJInlHRigiIiNJInhHRigiIidGOSIiIiwkRjpGOTckRj0sJkY5RjxGOCEiJ0knTWF0cml4R0YlNyMtRkE2Iy9JJCVpZEdGKEYx H1:=subs(critpoints[1], H); LV9JLFR5cGVzZXR0aW5nRzYkJSpwcm90ZWN0ZWRHSShfc3lzbGliRzYiSSxtcHJpbnRzbGFzaEdGKDYkNyM+SSNIMUdGKC1JJ1JUQUJMRUdGKDYlIipreUdQIi1JJ01BVFJJWEdGKDYjNyQ3JCQiKz8/Ly1cISIqJCIrK1d3InAiRjk3JEY6JCIrU052PiYpRjlJJ01hdHJpeEdGJTcjLUY/NiMvSSQlaWRHRihGMQ== Problem 5. In each part, find the critical points of the function. Classify each critical point as a local max, local min, saddle point, or degenerate critical point. Part A. f := x^3/3 +x*y+y^2-5*x -1; LV9JLFR5cGVzZXR0aW5nRzYkJSpwcm90ZWN0ZWRHSShfc3lzbGliRzYiSSxtcHJpbnRzbGFzaEdGKDYkNyM+SSJmR0YoLCwqJEkieEdGKCIiJCMiIiJGMSomRjBGM0kieUdGKEYzRjMqJEY1IiIjRjNGMCEiJiEiIkYzNyNGLg== Part B. f := x^3+3*x*y+2*x^2+x*y^2-x+y+1; LV9JLFR5cGVzZXR0aW5nRzYkJSpwcm90ZWN0ZWRHSShfc3lzbGliRzYiSSxtcHJpbnRzbGFzaEdGKDYkNyM+SSJmR0YoLDAqJEkieEdGKCIiJCIiIiomRjBGMkkieUdGKEYyRjEqJEYwIiIjRjYqJkYwRjJGNEY2RjJGMCEiIkY0RjJGMkYyNyNGLg== Part C. f := z^4+x^2*y^2+4*y^2*z^2+x^4-10*y^2*x+y*x+x+y+z; LV9JLFR5cGVzZXR0aW5nRzYkJSpwcm90ZWN0ZWRHSShfc3lzbGliRzYiSSxtcHJpbnRzbGFzaEdGKDYkNyM+SSJmR0YoLDQqJEkiekdGKCIiJSIiIiomSSJ4R0YoIiIjSSJ5R0YoRjVGMiomRjZGNUYwRjVGMSokRjRGMUYyKiZGNEYyRjZGNSEjNSomRjRGMkY2RjJGMkY0RjJGNkYyRjBGMjcjRi4= Part D. For one of the functions in Part A or Part B, try to plot graphs of the function near the critical points to illustrate the behaviour you found. It may help to translate the coordinates so the critical point is at the origin.