// Numbas version: exam_results_page_options {"name": "Maria's copy of Integration by partial fractions", "extensions": [], "custom_part_types": [], "resources": [], "navigation": {"allowregen": true, "showfrontpage": false, "preventleave": false, "typeendtoleave": false}, "question_groups": [{"pickingStrategy": "all-ordered", "questions": [{"type": "question", "parts": [{"scripts": {}, "type": "gapfill", "gaps": [{"answer": "({d-a*c}/{b-a})*ln(x+{a})+({d-b*c}/{a-b})*ln(x+{b})+C", "type": "jme", "answersimplification": "std", "showCorrectAnswer": true, "vsetrangepoints": 5, "expectedvariablenames": [], "vsetrange": [11, 12], "checkingtype": "absdiff", "scripts": {}, "notallowed": {"showStrings": false, "message": "

Input all numbers as fractions or integers and not decimals.

", "strings": ["."], "partialCredit": 0}, "marks": 3, "showpreview": true, "checkvariablenames": false, "checkingaccuracy": 0.0001}], "showCorrectAnswer": true, "stepsPenalty": 1, "marks": 0, "prompt": "\n

$I=\\;$[[0]]

\n

Input all numbers as fractions or integers and not decimals.

\n

Input the constant of integration as $C$.

\n

Click on Show steps for help if you need it. You will lose 1 mark if you do so.

\n \n ", "steps": [{"scripts": {}, "type": "information", "prompt": "\n

Use partial fractions in order to write:
\\[\\simplify[std]{({c}*x+{d})/((x +{a})*(x+{b}))}\\; = \\simplify[std]{A/(x+{a})+B/(x+{b})}\\]

\n

for suitable integers or fractions $A$ and $B$.

\n ", "showCorrectAnswer": true, "marks": 0}]}], "question_groups": [{"pickingStrategy": "all-ordered", "name": "", "questions": [], "pickQuestions": 0}], "functions": {}, "tags": ["2 distinct linear factors", "Calculus", "calculus", "checked2015", "compare coefficients", "identify coefficients", "integration", "logarithms", "MAS1601", "mas1601", "partial fractions", "Steps", "steps", "two distinct linear factors"], "advice": "\n

Using partial fractions we have to find $A$ and $B$ such that:
\\[\\simplify[std]{({c}*x+{d})/((x +{a})*(x+{b}))}\\;= \\simplify[std]{A/(x+{a})+B/(x+{b})}\\]
Multiplying both sides of the equation by $\\displaystyle \\simplify[std]{1/((x +{a})*(x+{b}))}$   we obtain:

\n

$\\simplify[std]{A*(x+{b})+B*(x+{a}) = {c}*x+{d}} \\Rightarrow \\simplify[std]{(A+B)*x+{b}*A+{a}*B={c}*x+{d}}$

\n

Identifying coefficients:

\n

Constant term: $\\simplify[std]{{b}*A+{a}*B = {d}}$

\n

Coefficent $x$: $ \\simplify[std]{A+B={c}}$ which gives $A =\\var{c} -B$

\n

On solving these equations we obtain $\\displaystyle \\simplify[std]{A = {d-a*c}/{b-a}}$ and $\\displaystyle \\simplify[std]{B={d-b*c}/{a-b}}$

\n

Which gives: \\[\\simplify[std]{({c}*x+{d})/((x +{a})*(x+{b}))}\\; =\\simplify[std]{ ({d-a*c}/{b-a})*(1/(x+{a}) )+({d-b*c}/{a-b})*(1/(x+{b}))}\\]

\n

So \\[\\begin{eqnarray*} I &=& \\simplify[std]{Int(({c}*x+{d})/((x +{a})*(x+{b})),x )}\\\\ &=& \\simplify[std]{({d-a*c}/{b-a})*(Int(1/(x+{a}),x)) +({d-b*c}/{a-b})Int(1/(x+{b}),x)}\\\\ &=& \\simplify[std]{({d-a*c}/{b-a})*ln(x+{a})+({d-b*c}/{a-b})*ln(x+{b})+C} \\end{eqnarray*}\\]

\n ", "showQuestionGroupNames": false, "name": "Maria's copy of Integration by partial fractions", "statement": "\n

Find the following integral.

\n

\\[I = \\simplify[std]{Int(({c}*x+{d})/((x +{a})*(x+{b})),x )}\\]

\n

Input all numbers as fractions or integers and not decimals.

\n

Input the constant of integration as $C$.

\n \n ", "variable_groups": [], "variablesTest": {"maxRuns": 100, "condition": ""}, "rulesets": {"std": ["all", "!collectNumbers", "fractionNumbers", "!noLeadingMinus"]}, "metadata": {"notes": "\n \t\t \t\t

5/08/2012:

\n \t\t \t\t

Added tags.

\n \t\t \t\t

Added description.

\n \t\t \t\t

Added decimal point as forbidden string.

\n \t\t \t\t

Note the checking range is chosen so that the arguments of the log terms are always positive - could have used abs - might be better?

\n \t\t \t\t

Improved display of Advice. 

\n \t\t \t\t

Added information about Show steps, also introduced penalty of 1 mark.

\n \t\t \t\t

Added !noLeadingMinus to ruleset std for display purposes.

\n \t\t \n \t\t", "licence": "Creative Commons Attribution 4.0 International", "description": "

Find $\\displaystyle\\int \\frac{ax+b}{(x+c)(x+d)}\\;dx,\\;a\\neq 0,\\;c \\neq d $.

"}, "ungrouped_variables": ["a", "c", "b", "d", "s3", "s2", "s1", "b1", "d1"], "variables": {"a": {"name": "a", "definition": "s1*random(1..9)", "templateType": "anything", "description": "", "group": "Ungrouped variables"}, "d": {"name": "d", "definition": "if(d1=a*c,if(d1+1=b*c,d1+2,d1+1),if(d1=b*c,if(d1+1=a*c,d1+2,d1+1),d1))", "templateType": "anything", "description": "", "group": "Ungrouped variables"}, "b": {"name": "b", "definition": "if(b1=a,b1+s3,b1)", "templateType": "anything", "description": "", "group": "Ungrouped variables"}, "s2": {"name": "s2", "definition": "random(1,-1)", "templateType": "anything", "description": "", "group": "Ungrouped variables"}, "s1": {"name": "s1", "definition": "random(1,-1)", "templateType": "anything", "description": "", "group": "Ungrouped variables"}, "s3": {"name": "s3", "definition": "random(1,-1)", "templateType": "anything", "description": "", "group": "Ungrouped variables"}, "c": {"name": "c", "definition": "random(2..9)", "templateType": "anything", "description": "", "group": "Ungrouped variables"}, "b1": {"name": "b1", "definition": "s2*random(1..9)", "templateType": "anything", "description": "", "group": "Ungrouped variables"}, "d1": {"name": "d1", "definition": "s3*random(1..9)", "templateType": "anything", "description": "", "group": "Ungrouped variables"}}, "preamble": {"css": "", "js": ""}, "contributors": [{"name": "Newcastle University Mathematics and Statistics", "profile_url": "https://numbas.mathcentre.ac.uk/accounts/profile/697/"}, {"name": "Maria Aneiros", "profile_url": "https://numbas.mathcentre.ac.uk/accounts/profile/3388/"}]}]}], "contributors": [{"name": "Newcastle University Mathematics and Statistics", "profile_url": "https://numbas.mathcentre.ac.uk/accounts/profile/697/"}, {"name": "Maria Aneiros", "profile_url": "https://numbas.mathcentre.ac.uk/accounts/profile/3388/"}]}