// Numbas version: exam_results_page_options {"name": "Find the fixed points of a 1D dynamical system", "extensions": [], "custom_part_types": [], "resources": [], "navigation": {"allowregen": true, "showfrontpage": false, "preventleave": false, "typeendtoleave": false}, "question_groups": [{"pickingStrategy": "all-ordered", "questions": [{"variable_groups": [], "variables": {"tol": {"templateType": "anything", "group": "Ungrouped variables", "definition": "0.001", "description": "", "name": "tol"}, "r1": {"templateType": "anything", "group": "Ungrouped variables", "definition": "random(2..9)", "description": "", "name": "r1"}, "ans3": {"templateType": "anything", "group": "Ungrouped variables", "definition": "precround(0.5*(c1+sqrt(c1^2-4*d1)),3)", "description": "", "name": "ans3"}, "c1": {"templateType": "anything", "group": "Ungrouped variables", "definition": "2*sqrt(d1)+random(1..9)", "description": "", "name": "c1"}, "ans1": {"templateType": "anything", "group": "Ungrouped variables", "definition": "0", "description": "", "name": "ans1"}, "d1": {"templateType": "anything", "group": "Ungrouped variables", "definition": "random(map(x^2,x,1..6))", "description": "", "name": "d1"}, "ans2": {"templateType": "anything", "group": "Ungrouped variables", "definition": "precround(0.5*(c1-sqrt(c1^2-4*d1)),3)", "description": "", "name": "ans2"}}, "ungrouped_variables": ["r1", "ans1", "ans2", "ans3", "tol", "c1", "d1"], "question_groups": [{"pickingStrategy": "all-ordered", "questions": [], "name": "", "pickQuestions": 0}], "name": "Find the fixed points of a 1D dynamical system", "functions": {}, "showQuestionGroupNames": false, "parts": [{"scripts": {}, "gaps": [{"showCorrectAnswer": true, "allowFractions": false, "scripts": {}, "type": "numberentry", "maxValue": "ans1+tol", "minValue": "ans1-tol", "correctAnswerFraction": false, "marks": 1, "showPrecisionHint": false}, {"showCorrectAnswer": true, "allowFractions": false, "scripts": {}, "type": "numberentry", "maxValue": "ans2+tol", "minValue": "ans2-tol", "correctAnswerFraction": false, "marks": 1, "showPrecisionHint": false}, {"showCorrectAnswer": true, "allowFractions": false, "scripts": {}, "type": "numberentry", "maxValue": "ans3+tol", "minValue": "ans3-tol", "correctAnswerFraction": false, "marks": 1, "showPrecisionHint": false}], "type": "gapfill", "prompt": "

\\[\\dot{x}=\\simplify{{-r1}*(x^3-{c1}*x^2+{d1}*x)}\\]

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There are three fixed points; enter them in ascending numerical order.

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Fixed point 1: $x_0=$ [[0]] (Enter your answer to 3d.p.)

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Fixed point 2: $x_0=$ [[1]] (Enter your answer to 3d.p.)

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Fixed point 3: $x_0=$ [[2]] (Enter your answer to 3d.p.)

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Find the fixed points $x_0$ of the following one-dimensional dynamical system $\\dot{x}=f(x)$.

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Fixed points of a 1D dynamical system.

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The fixed points are given by $\\dot{x}=0$.

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Rewrite the system as

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\\[\\dot{x}=\\simplify{{-r1}*x*(x^2-{c1}*x+{d1})},\\]

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then $\\dot{x}=0\\implies x=0$ (which is the first fixed point) or $\\simplify{x^2-{c1}*x+{d1}=0}$.

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Then solve the quadratic equation for $x$ to determine the other two fixed points.

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The three fixed points are therefore $x_0=\\var{ans1}$, $x_0=\\var{ans2}$, and $x_0=\\var{ans3}$ to 3d.p.

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