// Numbas version: finer_feedback_settings
{"name": "Alex's copy of Simon's copy of Lois's copy of Matrix Multiplication 1", "extensions": [], "custom_part_types": [], "resources": [], "navigation": {"allowregen": true, "showfrontpage": false, "preventleave": false, "typeendtoleave": false}, "question_groups": [{"pickingStrategy": "all-ordered", "questions": [{"functions": {}, "ungrouped_variables": ["ba21", "a21", "a22", "ba22", "cb21", "b22", "b21", "cb22", "ac22", "ac21", "ab22", "ab21", "b12", "b11", "c12", "c11", "c22", "a11", "cb11", "cb12", "a12", "c21", "ba11", "ba12", "ab12", "ab11", "ac12", "ac11"], "name": "Alex's copy of Simon's copy of Lois's copy of Matrix Multiplication 1", "tags": ["matrices", "matrix", "matrix multiplication", "matrix product", "multiplication of matrices", "multiplying matrices", "product of matrices"], "preamble": {"css": "", "js": ""}, "advice": "<h4>a)</h4>\n<p>\\[ \\begin{eqnarray*} AB &amp;=&amp; \\begin{pmatrix} \\var{a11}&amp;\\var{a12}\\\\ \\var{a21}&amp;\\var{a22}\\\\ \\end{pmatrix}\\begin{pmatrix} \\var{b11}&amp;\\var{b12}\\\\ \\var{b21}&amp;\\var{b22}\\\\ \\end{pmatrix}\\\\ &amp;=&amp; \\begin{pmatrix} \\simplify[]{{a11}{b11}+{a12}{b21}}&amp;\\simplify[]{{a11}{b12}+{a12}{b22}}\\\\ \\simplify[]{{a21}{b11}+{a22}{b21}}&amp;\\simplify[]{{a21}{b12}+{a22}{b22}}\\\\ \\end{pmatrix}\\\\ &amp;=&amp; \\begin{pmatrix} \\var{ab11}&amp;\\var{ab12}\\\\ \\var{ab21}&amp;\\var{ab22}\\\\ \\end{pmatrix} \\end{eqnarray*} \\]</p>\n<p></p>\n<h4>b)</h4>\n<p>\\[ \\begin{eqnarray*} CB &amp;=&amp; \\begin{pmatrix} \\var{c11}&amp;\\var{c12}\\\\ \\var{c21}&amp;\\var{c22}\\\\ \\end{pmatrix}\\begin{pmatrix} \\var{b11}&amp;\\var{b12}\\\\ \\var{b21}&amp;\\var{b22}\\\\ \\end{pmatrix}\\\\ &amp;=&amp; \\begin{pmatrix} \\simplify[]{{c11}{b11}+{c12}{b21}}&amp;\\simplify[]{{c11}{b12}+{c12}{b22}}\\\\ \\simplify[]{{c21}{b11}+{c22}{b21}}&amp;\\simplify[]{{c21}{b12}+{a22}{b22}}\\\\ \\end{pmatrix}\\\\ &amp;=&amp; \\begin{pmatrix} \\var{cb11}&amp;\\var{cb12}\\\\ \\var{cb21}&amp;\\var{cb22}\\\\ \\end{pmatrix} \\end{eqnarray*} \\]</p>\n<p>More information on multiplying matrices can be found in this <a href=\"http://www.mathcentre.ac.uk/resources/Engineering%20maths%20first%20aid%20kit/latexsource%20and%20diagrams/5_3.pdf\">Mathcentre leaflet</a>.</p>", "rulesets": {"std": ["all", "fractionNumbers", "!collectNumbers"]}, "parts": [{"prompt": "<p>$AB = \\begin{pmatrix} \\var{a11}&amp;\\var{a12}\\\\ \\var{a21}&amp;\\var{a22}\\\\ \\end{pmatrix}\\begin{pmatrix} \\var{b11}&amp;\\var{b12}\\\\ \\var{b21}&amp;\\var{b22}\\\\ \\end{pmatrix} = $ [[0]]</p>", "variableReplacements": [], "variableReplacementStrategy": "originalfirst", "gaps": [{"numRows": "2", "numColumns": "2", "type": "matrix", "allowFractions": false, "variableReplacements": [], "markPerCell": false, "variableReplacementStrategy": "originalfirst", "correctAnswerFractions": false, "showCorrectAnswer": true, "correctAnswer": "matrix([\n    [ab11,ab12],\n    [ab21,ab22]\n])", "scripts": {}, "marks": 1, "tolerance": 0, "allowResize": false}], "showCorrectAnswer": true, "scripts": {}, "marks": 0, "type": "gapfill"}, {"prompt": "<p>$CB = \\begin{pmatrix} \\var{c11}&amp;\\var{c12}\\\\ \\var{c21}&amp;\\var{c22}\\\\ \\end{pmatrix} \\begin{pmatrix} \\var{b11}&amp;\\var{b12}\\\\ \\var{b21}&amp;\\var{b22}\\\\ \\end{pmatrix}=$&nbsp;[[0]]</p>", "variableReplacements": [], "variableReplacementStrategy": "originalfirst", "gaps": [{"numRows": "2", "numColumns": "2", "type": "matrix", "allowFractions": false, "variableReplacements": [], "markPerCell": false, "variableReplacementStrategy": "originalfirst", "correctAnswerFractions": false, "showCorrectAnswer": true, "correctAnswer": "matrix([\n    [cb11,cb12],\n    [cb21,cb22]\n])", "scripts": {}, "marks": 1, "tolerance": 0, "allowResize": false}], "showCorrectAnswer": true, "scripts": {}, "marks": 0, "type": "gapfill"}], "statement": "<p><br/>Let <br/>\\[A=\\begin{pmatrix} \\var{a11}&amp;\\var{a12}\\\\ \\var{a21}&amp;\\var{a22}\\\\ \\end{pmatrix},\\;\\; B=\\begin{pmatrix} \\var{b11}&amp;\\var{b12}\\\\ \\var{b21}&amp;\\var{b22}\\\\ \\end{pmatrix},\\;\\; C=\\begin{pmatrix} \\var{c11}&amp;\\var{c12}\\\\ \\var{c21}&amp;\\var{c22}\\\\ \\end{pmatrix}\\]<br/>Calculate the following products of these matrices:</p>", "type": "question", "variable_groups": [], "variablesTest": {"maxRuns": 100, "condition": ""}, "question_groups": [{"pickingStrategy": "all-ordered", "name": "", "questions": [], "pickQuestions": 0}], "variables": {"ba21": {"definition": "b21*a11+b22*a21", "templateType": "anything", "group": "Ungrouped variables", "name": "ba21", "description": ""}, "a21": {"definition": "random(-2..2)", "templateType": "anything", "group": "Ungrouped variables", "name": "a21", "description": ""}, "a22": {"definition": "random(1..3)", "templateType": "anything", "group": "Ungrouped variables", "name": "a22", "description": ""}, "ba22": {"definition": "b21*a12+b22*a22", "templateType": "anything", "group": "Ungrouped variables", "name": "ba22", "description": ""}, "cb21": {"definition": "c21*b11+c22*b21", "templateType": "anything", "group": "Ungrouped variables", "name": "cb21", "description": ""}, "b22": {"definition": "random(-3..-1)", "templateType": "anything", "group": "Ungrouped variables", "name": "b22", "description": ""}, "b21": {"definition": "random(2,3)", "templateType": "anything", "group": "Ungrouped variables", "name": "b21", "description": ""}, "cb22": {"definition": "c21*b12+c22*b22", "templateType": "anything", "group": "Ungrouped variables", "name": "cb22", "description": ""}, "ac22": {"definition": "a21*c12+a22*c22", "templateType": "anything", "group": "Ungrouped variables", "name": "ac22", "description": ""}, "ac21": {"definition": "a21*c11+a22*c21", "templateType": "anything", "group": "Ungrouped variables", "name": "ac21", "description": ""}, "ab22": {"definition": "a21*b12+a22*b22", "templateType": "anything", "group": "Ungrouped variables", "name": "ab22", "description": ""}, "ab21": {"definition": "a21*b11+a22*b21", "templateType": "anything", "group": "Ungrouped variables", "name": "ab21", "description": ""}, "b12": {"definition": "random(-3..1)", "templateType": "anything", "group": "Ungrouped variables", "name": "b12", "description": ""}, "b11": {"definition": "random(-3,-1,0,3)", "templateType": "anything", "group": "Ungrouped variables", "name": "b11", "description": ""}, "c12": {"definition": "a12+b12", "templateType": "anything", "group": "Ungrouped variables", "name": "c12", "description": ""}, "c11": {"definition": "random(1,0,4)", "templateType": "anything", "group": "Ungrouped variables", "name": "c11", "description": ""}, "c22": {"definition": "random(0,1)", "templateType": "anything", "group": "Ungrouped variables", "name": "c22", "description": ""}, "a11": {"definition": "random(-2,1,2)", "templateType": "anything", "group": "Ungrouped variables", "name": "a11", "description": ""}, "cb11": {"definition": "c11*b11+c12*b21", "templateType": "anything", "group": "Ungrouped variables", "name": "cb11", "description": ""}, "cb12": {"definition": "c11*b12+c12*b22", "templateType": "anything", "group": "Ungrouped variables", "name": "cb12", "description": ""}, "a12": {"definition": "random(1..4)", "templateType": "anything", "group": "Ungrouped variables", "name": "a12", "description": ""}, "c21": {"definition": "random(2..5)", "templateType": "anything", "group": "Ungrouped variables", "name": "c21", "description": ""}, "ba11": {"definition": "b11*a11+b12*a21", "templateType": "anything", "group": "Ungrouped variables", "name": "ba11", "description": ""}, "ba12": {"definition": "b11*a12+b12*a22", "templateType": "anything", "group": "Ungrouped variables", "name": "ba12", "description": ""}, "ab12": {"definition": "a11*b12+a12*b22", "templateType": "anything", "group": "Ungrouped variables", "name": "ab12", "description": ""}, "ab11": {"definition": "a11*b11+a12*b21", "templateType": "anything", "group": "Ungrouped variables", "name": "ab11", "description": ""}, "ac12": {"definition": "a11*c12+a12*c22", "templateType": "anything", "group": "Ungrouped variables", "name": "ac12", "description": ""}, "ac11": {"definition": "a11*c11+a12*c21", "templateType": "anything", "group": "Ungrouped variables", "name": "ac11", "description": ""}}, "showQuestionGroupNames": false, "metadata": {"notes": "\n        \t\t                \t\t<p><strong>10/07/2012:</strong></p>\n        \t\t                \t\t<p>Added tags.</p>\n        \t\t                \t\t<p>Display of matrices looks untidy when individual components include negative numbers.</p>\n        \t\t                \t\t<p>Is it worthwhile restricting all components of matrices to be non zero?</p>\n        \t\t                \t\t<p>Question appears to be working correctly.</p>\n        \t\t                \n        \t\t", "description": "<p>Multiplication of $2 \\times 2$ matrices.</p>", "licence": "Creative Commons Attribution 4.0 International"}, "contributors": [{"name": "Alex Van den Hof", "profile_url": "https://numbas.mathcentre.ac.uk/accounts/profile/1273/"}]}]}], "contributors": [{"name": "Alex Van den Hof", "profile_url": "https://numbas.mathcentre.ac.uk/accounts/profile/1273/"}]}