By dragging the points A, B, C, D and E, construct the graph of the function $y=\\simplify[all]{{a}*x^2+{b}*x+{c}}$.
\nNote that in order to be marked correct, the points need to be within 0.2 of their correct $y$-values.
\nAlso note that you have to drag each of the points in order to be able to submit your answer.
", "advice": "The correct graph is shown below.
\n{graph(a,b,c)}
", "rulesets": {}, "extensions": ["jsxgraph"], "variables": {"b": {"name": "b", "group": "Ungrouped variables", "definition": "random(-5..5 except 0)", "description": "The function is f(x)=ax^2+bx+c.
", "templateType": "anything"}, "c": {"name": "c", "group": "Ungrouped variables", "definition": "random(-9..9)", "description": "The function is f(x)=ax^2+bx+c.
", "templateType": "anything"}, "a": {"name": "a", "group": "Ungrouped variables", "definition": "random(2..5)", "description": "The function is f(x)=ax^2+bx+c.
", "templateType": "anything"}}, "variablesTest": {"condition": "4*a+2*b+c<=10 and 4*a+2*b+c>=-10 and 4*a-2*b+c<=10 and 4*a-2*b+c>=-10 and (-b/(2*a) < -2 or -b/(2*a) >2 or (-(b^2-4*a*c)/(4*a) <= 10 and -(b^2-4*a*c)/(4*a) >= -10))", "maxRuns": "200"}, "ungrouped_variables": ["a", "b", "c"], "variable_groups": [], "functions": {"graph": {"parameters": [["a", "number"], ["b", "number"], ["c", "number"]], "type": "html", "language": "javascript", "definition": "// set up the board\nvar div = Numbas.extensions.jsxgraph.makeBoard('500px','500px',{boundingBox:[-2.5,11,2.5,-11],grid:true,withLabel:true,ticks:false});\n\nvar board = div.board;\n\nvar d = board.create('point',[2.1,0],{size:-1,name:'x'});\nd.setProperty({fixed:true});\nvar f = board.create('point',[0,10],{size:-1,name:'y'});\nf.setProperty({fixed:true});\nvar e = board.create('point',[-2,4*a-2*b+c],{size:5,name:'A'});\ne.setProperty({fixed:true});\nvar g = board.create('point',[-1,a-b+c],{size:5,name:'B'});\ng.setProperty({fixed:true});\nvar e = board.create('point',[0,c],{size:5,name:'C'});\ne.setProperty({fixed:true});\nvar e = board.create('point',[1,a+b+c],{size:5,name:'D'});\ne.setProperty({fixed:true});\nvar e = board.create('point',[2,4*a+2*b+c],{size:5,name:'E'});\ne.setProperty({fixed:true});\n\nboard.create('functiongraph',[function(x){ return a*x*x+b*x+c;},-2,2],{strokeColor:'blue',strokeWidth:2});\n\nreturn div;"}}, "preamble": {"js": "function dragpoint_board() {\n var scope = question.scope;\n \n var a = scope.variables.a.value;\n var b = scope.variables.b.value;\n var c = scope.variables.c.value;\n\n \n var div = Numbas.extensions.jsxgraph.makeBoard('500px','500px',{boundingBox:[-2.5,11,2.5,-11],grid:true,withLabel:true});\n $(question.display.html).find('#dragpoint').append(div);\n\n var board = div.board;\n \n// ceeate axis labels\n \n var label1 = board.create('point',[2.1,0.2],{name:'X',size:-1});\n label1.setProperty({fixed:true});\n var label2 = board.create('point',[0,10.3],{name:'y',size:-1});\n label2.setProperty({fixed:true});\n \n \n \n //create draggable points\n\n\n var line0 = board.create('line',[[-2,0],[-2,1]],{visible: false});\n var np0 = board.create('glider',[-2,8.5,line0],\n {\n name:'A',\n size:5\n }\n );\n\n var line1 = board.create('line',[[-1,0],[-1,1]],{visible: false});\n var np1 = board.create('glider',[-1,8.5,line1],\n {\n name:'B',\n size:5\n }\n );\n \n var line2 = board.create('line',[[0,0],[0,1]],{visible: false});\n var np2 = board.create('glider',[0,8.5,line2],\n {\n name:'C',\n size:5,\n }\n );\n \n var line3 = board.create('line',[[1,0],[1,1]],{visible: false});\n var np3 = board.create('glider',[1,8.5,line3],\n {\n name:'D',\n size:5\n }\n );\n var line4 = board.create('line',[[2,0],[2,1]],{visible: false});\n var np4 = board.create('glider',[2,8.5,line4],\n {\n name:'E',\n size:5\n }\n );\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 = 5;\n var points = [np0, np1, np2, np3, np4];\n \n \n // this function sets up the i^th point\n function make_point(i) {\n \n var point = points[i];\n \n var x=point[0];\n var y=point[1];\n \n // the contents of the input box for this point\n var xstudentAnswer = question.parts[0].gaps[i].display.studentAnswer;\n\n \n // when the student drags the point, update the gapfill input\n point.on('drag',function(){\n var x = Numbas.math.niceNumber(point.X());\n var y = Numbas.math.niceNumber(point.Y());\n var diff = y-(a*x*x+b*x+c);\n xstudentAnswer(diff);\n });\n \n }\n \n // create each point\n for(var i=0;i