// Numbas version: finer_feedback_settings {"name": "CF Maths Januaray test mock paper Partial Fractions 1", "extensions": [], "custom_part_types": [], "resources": [], "navigation": {"allowregen": true, "showfrontpage": false, "preventleave": false, "typeendtoleave": false}, "question_groups": [{"pickingStrategy": "all-ordered", "questions": [{"functions": {}, "ungrouped_variables": ["a", "c", "b", "d", "nb", "a1", "a2", "s1", "a_", "c_", "b_", "d_", "nb_", "a1_", "a2_", "s1_"], "name": "CF Maths Januaray test mock paper Partial Fractions 1", "tags": ["algebra", "algebraic fractions", "algebraic manipulation", "combining algebraic fractions", "common denominator"], "advice": "
a)
\nWe use partial fractions to find $A$ and $B$ such that:
\\[ \\simplify[std]{({a*a2+c*a1}*x+{c*b+a*d})/(({a1}x +{b})*({a2}x+{d}))} \\;\\;\\;=\\simplify[std]{ A/({a1}x+{b})+B/({a2}x+{d})}\\]
Dividing both sides of the equation by $\\displaystyle \\simplify[std]{1/( ({a1}x+{b})({a2}x+{d}) )}\\;\\;$ we obtain:
\n$\\simplify[std]{A*({a2}x+{d})+B*({a1}x+{b}) = {a*a2+c*a1}*x+{a*d+c*b}} \\Rightarrow \\simplify[std]{({a2}A+{a1}B)*x+{d}*A+{b}*B={a*a2+c*a1}*x+{a*d+c*b}}$
\nIdentifying coefficients:
\nConstant term: $\\simplify[std]{ {d}*A+{b}*B={a*d+c*b} }$
\nCoefficent $x$: $ \\simplify[std]{ {a2}A+{a1}B = {a*a2+c*a1} }$
\nOn solving these equations we obtain $A = \\var{a}$ and $B=\\var{c}$
\nWhich gives:\\[ \\simplify[std]{({a*a2+c*a1}*x+{c*b+a*d})/(({a1}x +{b})*({a2}x+{d}))}\\;\\;= \\simplify[std]{{a}/({a1}x+{b})+{c}/({a2}x+{d})}\\]
\n\nb)
\nWe use partial fractions to find $A$ and $B$ such that:
\\[ \\simplify[std]{({a_*a2_+c_*a1_}*x+{c_*b_+a_*d_})/(({a1_}x +{b_})*({a2_}x+{d_}))} \\;\\;\\;=\\simplify[std]{ A/({a1_}x+{b_})+B/({a2_}x+{d_})}\\]
Dividing both sides of the equation by $\\displaystyle \\simplify[std]{1/( ({a1_}x+{b_})({a2_}x+{d_}) )}\\;\\;$ we obtain:
\n$\\simplify[std]{A*({a2_}x+{d_})+B*({a1_}x+{b_}) = {a_*a2_+c_*a1_}*x+{a_*d_+c_*b_}} \\Rightarrow \\simplify[std]{({a2_}A+{a1_}B)*x+{d_}*A+{b_}*B={a_*a2_+c_*a1_}*x+{a_*d_+c_*b_}}$
\nIdentifying coefficients:
\nConstant term: $\\simplify[std]{ {d_}*A+{b_}*B={a_*d_+c_*b_} }$
\nCoefficent $x$: $ \\simplify[std]{ {a2_}A+{a1_}B = {a_*a2_+c_*a1_} }$
\nOn solving these equations we obtain $A = \\var{a_}$ and $B=\\var{c_}$
\nWhich gives:\\[ \\simplify[std]{({a_*a2_+c_*a1_}*x+{c_*b_+a_*d_})/(({a1_}x +{b_})*({a2_}x+{d_}))}\\;\\;= \\simplify[std]{{a_}/({a1_}x+{b_})+{c_}/({a2_}x+{d_})}\\]
", "rulesets": {"std": ["all", "!collectNumbers", "fractionNumbers", "!noLeadingMinus"]}, "parts": [{"prompt": "Split \\[\\simplify{({a*a2 + c*a1} * x + {a * d + c * b})/ (({a1}*x + {b}) * ({a2}*x + {d}))}\\] into partial fractions.
\nInput the partial fractions here: [[0]].
\n\n
", "variableReplacements": [], "variableReplacementStrategy": "originalfirst", "gaps": [{"notallowed": {"message": "
Input as the sum of partial fractions.
", "showStrings": false, "strings": [")(", ")*("], "partialCredit": 0}, "variableReplacements": [], "expectedvariablenames": [], "checkingaccuracy": 1e-05, "type": "jme", "showpreview": true, "vsetrangepoints": 5, "variableReplacementStrategy": "originalfirst", "showCorrectAnswer": true, "answersimplification": "std", "scripts": {}, "answer": "{a} / ({a1}*x + {b}) + ({c} / ({a2}*x + {d}))", "marks": 2, "checkvariablenames": false, "checkingtype": "absdiff", "vsetrange": [10, 11]}], "showCorrectAnswer": true, "scripts": {}, "marks": 0, "type": "gapfill"}, {"prompt": "Split \\[\\simplify{({a_*a2_ + c_*a1_} * x + {a_ * d_ + c_ * b_})/ (({a1_}*x + {b_}) * ({a2_}*x + {d_}))}\\] into partial fractions.
\nInput the partial fractions here: [[0]].
\n\n
", "variableReplacements": [], "variableReplacementStrategy": "originalfirst", "gaps": [{"notallowed": {"message": "
Input as the sum of partial fractions.
", "showStrings": false, "strings": [")(", ")*("], "partialCredit": 0}, "variableReplacements": [], "expectedvariablenames": [], "checkingaccuracy": 1e-05, "type": "jme", "showpreview": true, "vsetrangepoints": 5, "variableReplacementStrategy": "originalfirst", "showCorrectAnswer": true, "answersimplification": "std", "scripts": {}, "answer": "{a_} / ({a1_}*x + {b_}) + ({c_} / ({a2_}*x + {d_}))", "marks": 2, "checkvariablenames": false, "checkingtype": "absdiff", "vsetrange": [10, 11]}], "showCorrectAnswer": true, "scripts": {}, "marks": 0, "type": "gapfill"}], "statement": "\n\n
\n ", "variable_groups": [], "variablesTest": {"maxRuns": 100, "condition": ""}, "preamble": {"css": "", "js": ""}, "variables": {"a": {"definition": "random(1..9)", "templateType": "anything", "group": "Ungrouped variables", "name": "a", "description": ""}, "c": {"definition": "random(-9..9 except 0)", "templateType": "anything", "group": "Ungrouped variables", "name": "c", "description": ""}, "b": {"definition": "random(-9..9 except 0)", "templateType": "anything", "group": "Ungrouped variables", "name": "b", "description": ""}, "nb_": {"definition": "if(c_<0,'taking away','adding')", "templateType": "anything", "group": "Ungrouped variables", "name": "nb_", "description": ""}, "d": {"definition": "random(-9..9 except [0,round(b*a2/a1)])", "templateType": "anything", "group": "Ungrouped variables", "name": "d", "description": ""}, "nb": {"definition": "if(c<0,'taking away','adding')", "templateType": "anything", "group": "Ungrouped variables", "name": "nb", "description": ""}, "a2_": {"definition": "1", "templateType": "anything", "group": "Ungrouped variables", "name": "a2_", "description": ""}, "a1": {"definition": " 1", "templateType": "anything", "group": "Ungrouped variables", "name": "a1", "description": ""}, "d_": {"definition": "random(-9..9 except [0,round(b*a2/a1)])", "templateType": "anything", "group": "Ungrouped variables", "name": "d_", "description": ""}, "a2": {"definition": "1", "templateType": "anything", "group": "Ungrouped variables", "name": "a2", "description": ""}, "c_": {"definition": "random(-9..9 except 0)", "templateType": "anything", "group": "Ungrouped variables", "name": "c_", "description": ""}, "s1_": {"definition": "if(c_<0,-1,1)", "templateType": "anything", "group": "Ungrouped variables", "name": "s1_", "description": ""}, "b_": {"definition": "random(-9..9 except 0)", "templateType": "anything", "group": "Ungrouped variables", "name": "b_", "description": ""}, "a1_": {"definition": "1", "templateType": "anything", "group": "Ungrouped variables", "name": "a1_", "description": ""}, "a_": {"definition": "random(1..9)", "templateType": "anything", "group": "Ungrouped variables", "name": "a_", "description": ""}, "s1": {"definition": "if(c<0,-1,1)", "templateType": "anything", "group": "Ungrouped variables", "name": "s1", "description": ""}}, "metadata": {"notes": "\n \t\t \t\t
5/08/2012:
\n \t\t \t\tAdded tags.
\n \t\t \t\tAdded description.
\n \t\t \t\tChanged to two questions, for the numerator and denomimator, rather than one as difficult to trap student input for this example. Still some ambiguity however.
\n \t\t \t\t12/08/2012:
\n \t\t \t\tBack to one input of a fraction and trapped input in Forbidden Strings.
\n \t\t \t\tUsed the except feature of ranges to get non-degenerate examples.
\n \t\t \t\tChecked calculation.OK.
\n \t\t \t\tImproved display in content areas.
\n \t\t \n \t\t", "description": "Split $\\displaystyle \\frac{ax+b}{(cx + d)(px+q)}$ into partial fractions.
", "licence": "Creative Commons Attribution 4.0 International"}, "type": "question", "showQuestionGroupNames": false, "question_groups": [{"name": "", "pickingStrategy": "all-ordered", "pickQuestions": 0, "questions": []}], "contributors": [{"name": "", "profile_url": "https://numbas.mathcentre.ac.uk/accounts/profile/514/"}]}]}], "contributors": [{"name": "", "profile_url": "https://numbas.mathcentre.ac.uk/accounts/profile/514/"}]}