// Numbas version: exam_results_page_options {"name": "Phil's copy of Graph of a quadratic function", "extensions": ["jsxgraph"], "custom_part_types": [], "resources": [], "navigation": {"allowregen": true, "showfrontpage": false, "preventleave": false}, "question_groups": [{"pickingStrategy": "all-ordered", "questions": [{"functions": {}, "ungrouped_variables": ["a", "c"], "name": "Phil's copy of Graph of a quadratic function", "tags": ["hwmacs", "jsxgraph", "Jsxgraph", "plot", "quadratic"], "advice": "", "rulesets": {"std": ["all", "fractionNumbers"]}, "parts": [{"prompt": "

The graph of this formula is:

", "matrix": ["if(a>0,1,0)", "if(a>0,0,1)"], "shuffleChoices": false, "marks": 0, "variableReplacements": [], "choices": ["

An upwards-opening parabola

", "

A downwards-opening parabola

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Fill in the table of values for \$y=\\simplify[std]{{a}x^2+{c}}\$:

\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n
\$x\$\$-3\$\$-2\$\$-1\$\$0\$\$1\$\$2\$\$3\$
\$y\$[[0]][[1]][[2]][[3]][[4]][[5]][[6]]
\n

Give the coordinates of the turning point of the parabola: \$\\bigg(\$[[0]]\$, \$ [[1]]\$\\bigg)\$

", "variableReplacements": [], "variableReplacementStrategy": "originalfirst", "gaps": [{"allowFractions": false, "variableReplacements": [], "maxValue": "0", "minValue": "0", "variableReplacementStrategy": "originalfirst", "correctAnswerFraction": false, "showCorrectAnswer": true, "scripts": {}, "marks": 0.5, "type": "numberentry", "showPrecisionHint": false}, {"allowFractions": false, "variableReplacements": [], "maxValue": "{c}", "minValue": "{c}", "variableReplacementStrategy": "originalfirst", "correctAnswerFraction": false, "showCorrectAnswer": true, "scripts": {}, "marks": 0.5, "type": "numberentry", "showPrecisionHint": false}], "showCorrectAnswer": true, "scripts": {}, "marks": 0, "type": "gapfill"}], "statement": "

You are given the quadratic formula

\n

\$y=\\simplify[std]{{a}x^2+{c}}\$

", "variable_groups": [], "variablesTest": {"maxRuns": 100, "condition": ""}, "preamble": {"css": "table#values th {\n background: none;\n text-align: center;\n}", "js": "function dragpoint_board() {\n var scope = question.scope;\n \n var a = scope.variables.a.value;\n var c = scope.variables.c.value;\n var maxy = Math.max(Math.abs(a*9+c),Math.abs(c));\n \n var div = Numbas.extensions.jsxgraph.makeBoard('250px','400px',{boundingBox:[-5,maxy+3,5,-maxy-3],grid:true});\n \$(question.display.html).find('#dragpoint').append(div);\n \n var board = div.board;\n \n //shorthand to evaluate a mathematical expression to a number\n function evaluate(expression) {\n try {\n var val = Numbas.jme.evaluate(expression,question.scope);\n return Numbas.jme.unwrapValue(val);\n }\n catch(e) {\n // if there's an error, return no number\n return NaN;\n }\n }\n \n // set up points array\n var num_points = 7;\n var points = [];\n \n \n // this function sets up the i^th point\n function make_point(i) {\n \n // calculate initial coordinates\n var x = i-(num_points-1)/2;\n \n // create an invisible vertical line for the point to slide along\n var line = board.create('line',[[x,0],[x,1]],{visible: false});\n \n // create the point\n var point = points[i] = board.create(\n 'glider',\n [i-(num_points-1)/2,0,line],\n {\n name:'',\n size:2,\n snapSizeY: 0.1, // the point will snap to y-coordinates which are multiples of 0.1\n snapToGrid: true\n }\n );\n \n // the contents of the input box for this point\n var studentAnswer = question.parts[1].gaps[i].display.studentAnswer;\n \n // watch the student's input and reposition the point when it changes. \n ko.computed(function() {\n y = evaluate(studentAnswer());\n if(!(isNaN(y)) && board.mode!=board.BOARD_MODE_DRAG) {\n point.moveTo([x,y],100);\n }\n });\n \n // when the student drags the point, update the gapfill input\n point.on('drag',function(){\n var y = Numbas.math.niceNumber(point.Y());\n studentAnswer(y);\n });\n \n }\n \n // create each point\n for(var i=0;iAdapted from a question written in Dutch by Carolijn Tacken.

", "description": "

Compute a table of values for a quadratic function. A JSXgraph plot shows the curve going through the entered values.

", "licence": "Creative Commons Attribution 4.0 International"}, "type": "question", "showQuestionGroupNames": false, "question_groups": [{"name": "", "pickingStrategy": "all-ordered", "pickQuestions": 0, "questions": []}], "contributors": [{"name": "Phil Barker", "profile_url": "https://numbas.mathcentre.ac.uk/accounts/profile/624/"}]}]}], "contributors": [{"name": "Phil Barker", "profile_url": "https://numbas.mathcentre.ac.uk/accounts/profile/624/"}]}