// Numbas version: exam_results_page_options {"name": "Partial fraction breakdown A,B & C: simple irreducible quadratic factor", "extensions": [], "custom_part_types": [], "resources": [], "navigation": {"allowregen": true, "showfrontpage": false, "preventleave": false, "typeendtoleave": false}, "question_groups": [{"pickingStrategy": "all-ordered", "questions": [{"statement": "

Find the partial fraction breakdown of the compound fraction:

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\\(Q(s)=\\frac{\\var{F}s+\\var{H}}{(s+\\var{a1})(s^2+\\simplify{{b1}^2})}\\)

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If the partial fraction breakdown is given by:

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\\(Q(s) =\\frac{A}{s+\\var{a1}}+\\frac{Bs+C}{s^2+\\simplify{{b1}^2}}\\)

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Calculate the values of \\(A, B\\) and \\(C\\) and give your answers as fractions

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\\(A=\\) [[0]]

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\\(B=\\) [[1]]

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\\(C=\\) [[2]]

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\\(Q(s)=\\frac{\\var{F}s+\\var{H}}{(s+\\var{a1})(s^2+\\simplify{{b1}^2})}=\\frac{A}{s+\\var{a1}}+\\frac{Bs+C}{s^2+\\simplify{{b1}^2}}\\)

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Multiply across by \\((s+\\var{a1})(s^2+\\simplify{{b1}^2})\\)

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\\(\\var{F}s+\\var{H}=A(s^2+\\simplify{{b1}^2})+Bs(s+\\var{a1})+C(s+\\var{a1})\\)

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let \\(s=-\\var{a1}\\)

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\\(\\var{F}(-\\var{a1})+\\var{H}=A(\\simplify{{b1}^2+{a1}^2})+B(0)+C(0)\\)

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\\(\\simplify{{F}*(-{a1})+{H}}=\\simplify{({b1}^2+{a1}^2)}A\\)

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\\(A=\\frac{\\simplify{-{F}*{a1}+{H}}}{\\simplify{({b1}^2+{a1}^2)}}\\)

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let \\(s=0\\)

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\\(\\var{H}=A(\\simplify{{b1}^2})+B(0)+C(\\var{a1})\\)

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\\(\\var{H}=(\\frac{\\simplify{-{F}*{a1}+{H}}}{\\simplify{({b1}^2+{a1}^2)}})*\\simplify{{b1}^2}+\\var{a1}C\\)

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\\(\\frac{\\simplify{{a1}^2*{H}+{b1}^2*{a1}*{F}}}{\\simplify{({b1}^2+{a1}^2)}}=\\var{a1}C\\)

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\\(C=\\frac{\\simplify{{a1}*{H}+{b1}^2*{F}}}{\\simplify{({b1}^2+{a1}^2)}}\\)

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Compare coefficients of \\(s^2\\)

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\\(0=A+B\\)

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\\(B=-A\\)

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\\(B=\\frac{\\simplify{{F}*{a1}-{H}}}{\\simplify{({b1}^2+{a1}^2)}}\\)

", "type": "question", "contributors": [{"name": "Frank Doheny", "profile_url": "https://numbas.mathcentre.ac.uk/accounts/profile/789/"}]}]}], "contributors": [{"name": "Frank Doheny", "profile_url": "https://numbas.mathcentre.ac.uk/accounts/profile/789/"}]}