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The student is asked to factorise a quadratic $x^2 + ax + b$. A custom marking script uses pattern matching to ensure that the student's answer is of the form $(x+a)(x+b)$, $(x+a)^2$, or $x(x+a)$.

\n

To find the script, look in the Scripts tab of part a.

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Factorise $\\simplify{x^2+{a+b}x+{a*b}}$

", "valuegenerators": [{"value": "", "name": "x"}], "showCorrectAnswer": true, "checkVariableNames": false, "checkingAccuracy": 0.001, "answer": "(x+{a})(x+{b})", "variableReplacements": [], "scripts": {"mark": {"script": "// Parse the student's answer as a syntax tree\nvar studentTree = Numbas.jme.compile(this.studentAnswer,Numbas.jme.builtinScope);\n\n// Create the pattern to match against \n// we just want two sets of brackets, each containing two terms\n// or one of the brackets might not have a constant term\n// or for repeated roots, you might write (x+a)^2\nvar rule = Numbas.jme.compile('m_any( (x+??)(x+??), (x+??)^2, x*(x+??) )');\n\n// Check the student's answer matches the pattern. \nvar m = Numbas.jme.display.matchTree(rule,studentTree,true);\n// If not, take away marks\nif(!m) {\n this.multCredit(0.5,'Your answer is not in the form $(\\\\dots)(\\\\dots)$.');\n}\n", "order": "after"}}}], "variable_groups": [], "ungrouped_variables": ["a", "b"], "extensions": [], "functions": {}, "rulesets": {}, "variablesTest": {"maxRuns": 100, "condition": ""}, "variables": {"a": {"description": "", "templateType": "anything", "group": "Ungrouped variables", "name": "a", "definition": "random(-5..5)"}, "b": {"description": "", "templateType": "anything", "group": "Ungrouped variables", "name": "b", "definition": "random(-5..5 except 0)"}}, "advice": "", "statement": "", "preamble": {"js": "", "css": ""}, "contributors": [{"name": "Christian Lawson-Perfect", "profile_url": "https://numbas.mathcentre.ac.uk/accounts/profile/7/"}, {"name": "Josh Lim", "profile_url": "https://numbas.mathcentre.ac.uk/accounts/profile/2990/"}]}]}], "contributors": [{"name": "Christian Lawson-Perfect", "profile_url": "https://numbas.mathcentre.ac.uk/accounts/profile/7/"}, {"name": "Josh Lim", "profile_url": "https://numbas.mathcentre.ac.uk/accounts/profile/2990/"}]}