// Numbas version: finer_feedback_settings {"name": "Luis's copy of Integration: Indefinite integral", "extensions": [], "custom_part_types": [], "resources": [], "navigation": {"allowregen": true, "showfrontpage": false, "preventleave": false, "typeendtoleave": false}, "question_groups": [{"pickingStrategy": "all-ordered", "questions": [{"tags": ["calculus", "Calculus", "checked2015", "constant of integration", "indefinite integration", "integration", "integration by substitution", "MAS1601", "mas1601", "standard integrals", "Steps", "steps", "substitution"], "statement": "\n\t \n\t \n\t
Find the following indefinite integral.
\n\t \n\t \n\t \n\tInput the constant of integration as $C$.
\n\t \n\t \n\t", "name": "Luis's copy of Integration: Indefinite integral", "metadata": {"notes": "\n\t\t2/08/2012:
\n\t\tAdded tags.
\n\t\tAdded description.
\n\t\tAdded decimal point to forbidden strings along with message to user re input of numbers.
\n\t\tAdded a Step and message about Show steps included - losing 1 mark if used as it gives the formula for finding the integral. Increased marks to 3 for the question, so that can cope with losing a mark for using Show steps.
\n\t\tChanged accuracy setting to relative difference of 0.00001 as we have negative powers.
\n\t\tChecked calculation. OK.
\n\t\tAdded message in prompt about including the constant of integration.
\n\t\tNoted issue with steps-answer order and the messages/marks generated.
\n\t\tChanged numerator to the range 2..5.
\n\t\tImproved display in Advice.
\n\t\t\n\t\t", "licence": "Creative Commons Attribution 4.0 International", "description": "
Find $\\displaystyle \\int \\frac{a}{(bx+c)^n}\\;dx$
"}, "ungrouped_variables": ["a", "b", "d", "n"], "parts": [{"prompt": "\n\t\t\t$\\displaystyle \\int \\simplify[std]{{b}/(({a}*x+{d})^{n})} dx= \\phantom{{}}$[[0]]
\n\t\t\tInput all numbers as integers or fractions and not decimals. Remember to include the constant of integration $C$.
\n\t\t\tClick on Show steps to get help. You will lose 1 mark by doing so.
\n\t\t\t", "type": "gapfill", "marks": 0, "showCorrectAnswer": true, "gaps": [{"checkvariablenames": false, "showCorrectAnswer": true, "answer": "(-{b})/({a*(n-1)}*({a}*x+{d})^{n-1}) + C", "vsetrange": [0, 1], "answersimplification": "std", "expectedvariablenames": [], "vsetrangepoints": 5, "type": "jme", "scripts": {}, "checkingtype": "reldiff", "notallowed": {"partialCredit": 0, "message": "Input all numbers as integers or fractions and not decimals.
", "showStrings": false, "strings": ["."]}, "marks": 3, "checkingaccuracy": 0.0001, "showpreview": true}], "stepsPenalty": 1, "scripts": {}, "steps": [{"prompt": "\\[\\int (ax+b)^n \\;dx = \\frac{1}{a(n+1)}(ax+b)^{n+1}+C\\]
", "type": "information", "marks": 0, "scripts": {}, "showCorrectAnswer": true}]}], "variables": {"d": {"definition": "random(1..9)", "name": "d", "templateType": "anything", "group": "Ungrouped variables", "description": ""}, "b": {"definition": "random(2..5)", "name": "b", "templateType": "anything", "group": "Ungrouped variables", "description": ""}, "a": {"definition": "random(2..9)", "name": "a", "templateType": "anything", "group": "Ungrouped variables", "description": ""}, "n": {"definition": "random(3..5)", "name": "n", "templateType": "anything", "group": "Ungrouped variables", "description": ""}}, "variable_groups": [], "preamble": {"css": "", "js": ""}, "type": "question", "rulesets": {"std": ["all", "!collectNumbers", "fractionNumbers", "!noLeadingMinus"], "surdf": [{"result": "(sqrt(b)*a)/b", "pattern": "a/sqrt(b)"}]}, "advice": "\n\tLet $y = \\simplify[std]{{a}*x+{d}}$. Then,
\\[\\simplify[std]{{b}/(({a}*x+{d})^{n})} = \\simplify[std]{{b}/(y^{n})}.\\]
Now,
\\[\\int \\simplify[std]{{b}/({a}*x+{d})^{n}} dx = \\int \\simplify[std]{{b}/(y^{n})} \\frac{dx}{dy} dy.\\]
Rearrange $y = \\simplify[std]{{a}x+{d}}$ to get $\\displaystyle x = \\simplify[std]{(y-{b})/{a}}$, and hence $\\displaystyle\\frac{dx}{dy} = \\frac{1}{\\var{a}}$.
\n\t$\\displaystyle \\int \\frac{1}{y^n} dx = -\\frac{1}{(n-1)y^{n-1}} + C$ is a standard integral, so we can now calculate the desired integral:
\n\t\\[\\int \\simplify[std]{{b}/(y^{n})} \\frac{dx}{dy} dy = \\simplify[std]{{b}/({n-1}*y^{n-1})} \\cdot \\frac{1}{\\var{a}} + C = \\simplify[std]{(-{b})/({a*(n-1)}*({a}*x+{d})^{n-1}) + C}.\\]
\n\t", "showQuestionGroupNames": false, "functions": {}, "variablesTest": {"maxRuns": 100, "condition": ""}, "question_groups": [{"name": "", "pickingStrategy": "all-ordered", "questions": [], "pickQuestions": 0}], "contributors": [{"name": "Newcastle University Mathematics and Statistics", "profile_url": "https://numbas.mathcentre.ac.uk/accounts/profile/697/"}, {"name": "Luis Hernandez", "profile_url": "https://numbas.mathcentre.ac.uk/accounts/profile/2870/"}]}]}], "contributors": [{"name": "Newcastle University Mathematics and Statistics", "profile_url": "https://numbas.mathcentre.ac.uk/accounts/profile/697/"}, {"name": "Luis Hernandez", "profile_url": "https://numbas.mathcentre.ac.uk/accounts/profile/2870/"}]}