// Numbas version: exam_results_page_options {"name": "Simple integrals #2", "extensions": [], "custom_part_types": [], "resources": [], "navigation": {"allowregen": true, "showfrontpage": false, "preventleave": false, "typeendtoleave": false}, "question_groups": [{"pickingStrategy": "all-ordered", "questions": [{"parts": [{"showCorrectAnswer": true, "showFeedbackIcon": true, "scripts": {}, "marks": 0, "variableReplacementStrategy": "originalfirst", "gaps": [{"variableReplacementStrategy": "originalfirst", "mustBeReducedPC": 0, "correctAnswerStyle": "plain", "allowFractions": false, "showFeedbackIcon": true, "maxValue": "{frac}*{factor1}*{factor2}", "precisionMessage": "You have not given your answer to the correct precision.", "correctAnswerFraction": false, "scripts": {}, "minValue": "{frac}*{factor1}*{factor2}", "notationStyles": ["plain", "en", "si-en"], "showCorrectAnswer": true, "variableReplacements": [], "precisionPartialCredit": "75", "marks": 1, "precision": "2", "precisionType": "dp", "showPrecisionHint": false, "type": "numberentry", "strictPrecision": false, "mustBeReduced": false}], "type": "gapfill", "variableReplacements": [], "prompt": "

Insert your answer correct to two decimal places

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Answer = [[0]]

"}], "statement": "

Evaluate the integral:

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\\(\\int_\\var{a2}^\\var{b2}\\int_\\var{a1}^\\var{b1}\\var{k1}e^{\\var{k2}x+\\var{k3}y}dx\\,dy\\)

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\\(\\int_\\var{a2}^\\var{b2}\\int_\\var{a1}^\\var{b1}\\var{k1}e^{\\var{k2}x+\\var{k3}y}dx\\,dy\\)

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Inner integral:

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\\(\\int_\\var{a1}^\\var{b1}\\var{k1}e^{\\var{k2}x+\\var{k3}y}dx\\)

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\\(=\\frac{\\var{k1}}{\\var{k2}}e^{\\var{k2}x+\\var{k3}y}\\big|_\\var{a1}^\\var{b1}\\)

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\\(=-\\frac{\\var{k1}}{\\var{k4}}e^{\\var{k2}x+\\var{k3}y}\\big|_\\var{a1}^\\var{b1}\\)

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\\(=-\\frac{\\var{k1}}{\\var{k4}}e^{\\simplify{{k2}*{b1}}+\\var{k3}y}-\\left(-\\frac{\\var{k1}}{\\var{k4}}e^{\\simplify{{k2}*{a1}}+\\var{k3}y}\\right)\\)

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\\(=-\\frac{\\var{k1}}{\\var{k4}}e^{\\simplify{{k2}*{b1}}+\\var{k3}y}+\\frac{\\var{k1}}{\\var{k4}}e^{\\simplify{{k2}*{a1}}+\\var{k3}y}\\)

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Outer integral:

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\\(\\int_\\var{a2}^\\var{b2}-\\frac{\\var{k1}}{\\var{k4}}e^{\\simplify{{k2}*{b1}}+\\var{k3}y}+\\frac{\\var{k1}}{\\var{k4}}e^{\\simplify{{k2}*{a1}}+\\var{k3}y}dy\\)

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\\(=-\\frac{\\var{k1}}{\\var{k4}}\\frac{1}{\\var{k3}}e^{\\simplify{{k2}*{b1}}+\\var{k3}y}+\\frac{\\var{k1}}{\\var{k4}}\\frac{1}{\\var{k3}}e^{\\simplify{{k2}*{a1}}+\\var{k3}y}\\big|_\\var{a2}^\\var{b2}\\)

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\\(=-\\frac{\\var{k1}}{\\simplify{{k4}*{k3}}}e^{\\simplify{{k2}*{b1}}+\\simplify{{k3}*{b2}}}+\\frac{\\var{k1}}{\\simplify{{k4}*{k3}}}e^{\\simplify{{k2}*{a1}}+\\simplify{{k3}*{b2}}}-\\left(-\\frac{\\var{k1}}{\\simplify{{k4}*{k3}}}e^{\\simplify{{k2}*{b1}}+\\simplify{{k3}*{a2}}}+\\frac{\\var{k1}}{\\simplify{{k4}*{k3}}}e^{\\simplify{{k2}*{a1}}+\\simplify{{k3}*{a2}}}\\right)\\)

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\\(=-\\frac{\\var{k1}}{\\simplify{{k4}*{k3}}}e^{\\simplify{{k2}*{b1}+{k3}*{b2}}}+\\frac{\\var{k1}}{\\simplify{{k4}*{k3}}}e^{\\simplify{{k2}*{a1}+{k3}*{b2}}}+\\frac{\\var{k1}}{\\simplify{{k4}*{k3}}}e^{\\simplify{{k2}*{b1}+{k3}*{a2}}}-\\frac{\\var{k1}}{\\simplify{{k4}*{k3}}}e^{\\simplify{{k2}*{a1}+{k3}*{a2}}}\\)

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\\(=-\\frac{\\var{k1}}{\\simplify{{k4}*{k3}}}\\left(e^{\\simplify{{k2}*{b1}+{k3}*{b2}}}-e^{\\simplify{{k2}*{a1}+{k3}*{b2}}}-e^{\\simplify{{k2}*{b1}+{k3}*{a2}}}+e^{\\simplify{{k2}*{a1}+{k3}*{a2}}}\\right)\\)

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\\(=\\simplify{{k1}/({k2}*{k3})}\\left(\\var{s1}-\\var{s2}-\\var{s3}+\\var{s4}\\right)\\)

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\\(=\\simplify{{frac}*{factor1}*{factor2}}\\)

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