// Numbas version: exam_results_page_options {"name": "Surds: Simplifying Expressions 5b - Rationalising the Denominator", "extensions": [], "custom_part_types": [], "resources": [], "navigation": {"allowregen": true, "showfrontpage": false, "preventleave": false, "typeendtoleave": false}, "question_groups": [{"pickingStrategy": "all-ordered", "questions": [{"name": "Surds: Simplifying Expressions 5b - Rationalising the Denominator", "tags": [], "metadata": {"description": "

Rewriting fractions involving surds by rationalising the denominator.

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Rationalise the denominator in the following expression:

\n

\\[\\simplify[unitFactor]{({a}+{sgn}*sqrt({b}))/sqrt({b})}\\]

", "advice": "

To rationalise the denominator of a fraction which has the form $\\frac{a\\pm\\sqrt{b}}{\\sqrt{b}}$, we must multiply the numerator and denominator by $\\sqrt{b}$.

\n

Therefore,

\n

{advice}

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\\\\[ \\\\begin{split} \\\\simplify{({a}+{sgn}*sqrt({b}))/sqrt({b})} &\\\\,=\\\\simplify{({a}+{sgn}*sqrt({b}))sqrt({b})/(sqrt({b})sqrt({b}))}\\\\\\\\ \\\\\\\\ &\\\\,= \\\\simplify{({a}sqrt({b})+{sgn*b})/{b}} \\\\\\\\\\\\\\\\&\\\\,= \\\\simplify[all]{(({a}sqrt({b})/{simp})+({sgn}*{b})/{simp})/{b/simp}} \\\\end{split} \\\\]

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\\\\[ \\\\begin{split} \\\\simplify{({a}+{sgn}*sqrt({b}))/sqrt({b})} &\\\\,=\\\\simplify{({a}+{sgn}*sqrt({b}))sqrt({b})/(sqrt({b})sqrt({b}))}\\\\\\\\ \\\\\\\\ &\\\\,= \\\\simplify{({a}sqrt({b})+{sgn*b})/{b}} \\\\end{split} \\\\]

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You can type sqrt(x) to get $\\sqrt{x}$.

", "answer": "({a/simp}*sqrt({b})+{sgn*b/simp})/{b/simp}", "answerSimplification": "all,simplifyFractions,cancelTerms", "showPreview": true, "checkingType": "absdiff", "checkingAccuracy": 0.001, "failureRate": 1, "vsetRangePoints": 5, "vsetRange": [0, 1], "checkVariableNames": false, "singleLetterVariables": false, "allowUnknownFunctions": true, "implicitFunctionComposition": false, "caseSensitive": false, "mustmatchpattern": {"pattern": "($n+`+-$n`?*sqrt($n))/$n`? `| `+-$n+`+-$n`?*sqrt($n)/$n`?", "partialCredit": 0, "message": "", "nameToCompare": ""}, "valuegenerators": []}], "partsMode": "all", "maxMarks": 0, "objectives": [], "penalties": [], "objectiveVisibility": "always", "penaltyVisibility": "always", "contributors": [{"name": "Ben McGovern", "profile_url": "https://numbas.mathcentre.ac.uk/accounts/profile/4872/"}]}]}], "contributors": [{"name": "Ben McGovern", "profile_url": "https://numbas.mathcentre.ac.uk/accounts/profile/4872/"}]}