// Numbas version: finer_feedback_settings {"name": "Maria's copy of Jo-Ann's copy of Integration by parts - logarithm", "extensions": [], "custom_part_types": [], "resources": [], "navigation": {"allowregen": true, "showfrontpage": false, "preventleave": false, "typeendtoleave": false}, "question_groups": [{"pickingStrategy": "all-ordered", "questions": [{"parts": [{"unitTests": [], "showCorrectAnswer": true, "prompt": "
$I=\\displaystyle \\int \\simplify[std]{({a}x)*ln({c}x)} dx $
\nThe formula for integration by parts is
\n\\[ \\int u\\frac{dv}{dx} dx = uv - \\int v \\frac{du}{dx} dx. \\]
\nWhat is the most suitable choice for $u$ and $\\frac{dv}{dx}$?
\n$u =\\;$[[0]]
\n$\\frac{dv}{dx} =\\;$[[1]]
\n", "extendBaseMarkingAlgorithm": true, "gaps": [{"unitTests": [], "checkingAccuracy": 0.001, "showPreview": true, "expectedVariableNames": [], "failureRate": 1, "variableReplacementStrategy": "originalfirst", "showFeedbackIcon": true, "vsetRange": [0, 1], "customMarkingAlgorithm": "", "checkVariableNames": false, "answerSimplification": "all", "vsetRangePoints": 5, "variableReplacements": [], "checkingType": "absdiff", "type": "jme", "answer": "ln({c}x)", "showCorrectAnswer": true, "marks": 1, "scripts": {}, "extendBaseMarkingAlgorithm": true}, {"unitTests": [], "checkingAccuracy": 0.001, "showPreview": true, "expectedVariableNames": [], "failureRate": 1, "variableReplacementStrategy": "originalfirst", "showFeedbackIcon": true, "vsetRange": [0, 1], "customMarkingAlgorithm": "", "checkVariableNames": false, "answerSimplification": "all", "vsetRangePoints": 5, "variableReplacements": [], "checkingType": "absdiff", "type": "jme", "answer": "{a}x", "showCorrectAnswer": true, "marks": 1, "scripts": {}, "extendBaseMarkingAlgorithm": true}], "variableReplacementStrategy": "originalfirst", "showFeedbackIcon": true, "customMarkingAlgorithm": "", "sortAnswers": false, "variableReplacements": [], "type": "gapfill", "marks": 0, "scripts": {}}, {"unitTests": [], "showCorrectAnswer": true, "prompt": "Hence find:
\n$\\frac{du}{dx} =\\;$[[0]]
\n$v =\\;$[[1]]
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\n$uv =\\;$[[0]]
\n$\\int v\\frac{du}{dx}\\mathrm{d}x = \\;$[[1]]$+C$
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\n$I=\\displaystyle \\int \\simplify[std]{({a}x)*ln({c}x)} dx = uv - \\int v \\frac{du}{dx} dx = \\;$[[0]]$+C$
\nInput all numbers as fractions or integers and not decimals.
", "extendBaseMarkingAlgorithm": true, "gaps": [{"unitTests": [], "checkingAccuracy": 0.001, "notallowed": {"message": "Do not input numbers as decimals, only as integers without the decimal point, or fractions
", "partialCredit": 0, "strings": ["."], "showStrings": false}, "showPreview": true, "expectedVariableNames": [], "failureRate": 1, "variableReplacementStrategy": "originalfirst", "showFeedbackIcon": true, "vsetRange": [0, 1], "customMarkingAlgorithm": "", "checkVariableNames": false, "answerSimplification": "std", "vsetRangePoints": 5, "variableReplacements": [], "checkingType": "absdiff", "type": "jme", "answer": "{a}x^2/2ln({c}x)-{a}x^2/4", "showCorrectAnswer": true, "marks": "2", "scripts": {}, "extendBaseMarkingAlgorithm": true}], "variableReplacementStrategy": "originalfirst", "showFeedbackIcon": true, "customMarkingAlgorithm": "", "sortAnswers": false, "variableReplacements": [], "type": "gapfill", "marks": 0, "scripts": {}}], "advice": "\\[ \\int u\\frac{dv}{dx} dx = uv - \\int v \\frac{du}{dx} dx. \\]
\nWe choose $u = \\simplify[std]{ln{c}x}$ and $\\displaystyle \\frac{dv}{dx} = \\simplify[std]{{a}x}$.
\nSo $\\displaystyle \\frac{du}{dx} = \\simplify[std]{1/x}$ and $\\displaystyle v = \\simplify[std]{({a}x^2/2)}$.
\nHence,
\\[ \\begin{eqnarray} \\int \\simplify[std]{({a}*x)*ln({c}*x)} dx &=& uv - \\int v \\frac{du}{dx} dx \\\\ &=& \\simplify[std]{(({a}*x^2)/2)*ln({c}*x) - Int(({a}*x/2),x)} \\\\ &=& \\simplify[std]{(({a}x^2)/2)*ln({c}*x) -({a}x^2/4) + C} \\end{eqnarray} \\]
Find $\\displaystyle \\int (ax)\\ln(cx)\\; dx $
"}, "variablesTest": {"condition": "", "maxRuns": 100}, "statement": "Find the following indefinite integral.
\nThis question is scaffolded - i.e. it takes you through answering the question step by step.
\nInput all numbers as fractions or integers and not decimals.
\nDon't forget $C$!
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