// Numbas version: finer_feedback_settings {"name": "Christian's copy of Applications of differentiation", "extensions": [], "custom_part_types": [], "resources": [], "navigation": {"allowregen": true, "showfrontpage": false, "preventleave": false, "typeendtoleave": false}, "question_groups": [{"pickingStrategy": "all-ordered", "questions": [{"functions": {}, "variables": {"z": {"templateType": "randrange", "name": "z", "description": "", "definition": "random(20 .. 30#0.5)", "group": "Ungrouped variables"}, "h": {"templateType": "randrange", "name": "h", "description": "", "definition": "random(0 .. 5#0.5)", "group": "Ungrouped variables"}, "g": {"templateType": "randrange", "name": "g", "description": "", "definition": "random(-10 .. 10#1)", "group": "Ungrouped variables"}, "c": {"templateType": "anything", "name": "c", "description": "", "definition": "random(2..7)", "group": "Ungrouped variables"}, "maximum": {"templateType": "anything", "name": "maximum", "description": "

Is the stationary point a maximum?

", "definition": "f<0", "group": "Ungrouped variables"}, "d": {"templateType": "anything", "name": "d", "description": "", "definition": "random(2..5)", "group": "Ungrouped variables"}, "f": {"templateType": "anything", "name": "f", "description": "", "definition": "random(-10..10 except 0)", "group": "Ungrouped variables"}, "t": {"templateType": "randrange", "name": "t", "description": "", "definition": "random(0 .. 1#0.1)", "group": "Ungrouped variables"}, "b": {"templateType": "anything", "name": "b", "description": "", "definition": "random(2..5)", "group": "Ungrouped variables"}, "a": {"templateType": "randrange", "name": "a", "description": "", "definition": "random(0 .. 10#0.5)", "group": "Ungrouped variables"}, "w": {"templateType": "randrange", "name": "w", "description": "", "definition": "random(2 .. 5#0.1)", "group": "Ungrouped variables"}}, "variablesTest": {"condition": "isclose(-g/(2f),2/3)", "maxRuns": "500"}, "rulesets": {"std": ["all", "fractionNumbers"]}, "extensions": [], "name": "Christian's copy of Applications of differentiation", "variable_groups": [], "tags": [], "ungrouped_variables": ["z", "c", "b", "d", "f", "w", "a", "g", "h", "t", "maximum"], "advice": "

Parts A and B

\n

Here, the question takes you throught the stages needed to find the solution. The reason we differentiate is that the derivative of a function tells us its gradient at a given point, and we want to find where the function has gradient zero because when the gradient is zero we either have a maximum or a minimum point.

\n

Part C

\n

The first part of this question is similar to parts A and B. The tricky bit is the second part! You need to work out the value of $t$ that produces the maximum piont but that is not the final answer - you need to use that value of $t$ to find the maximum height, which you do by substituting $t$ into the original function to find $y$.

", "metadata": {"licence": "Creative Commons Attribution 4.0 International", "description": ""}, "statement": "", "preamble": {"js": "", "css": ""}, "parts": [{"prompt": "

Find the gradient of the curve $y$ at the point $x=\\var{d}$, giving your answer to $2$ decimal places if necessary.

\n

\\[ y = \\simplify{ {a}*x^2 + {b}x + {c}} \\]

\n

Firstly, differentiate.

\n

$\\displaystyle \\frac{dy}{dx}=$ [[1]]

\n

Gradient at $x=\\var{d}\\;$ is [[0]]

", "scripts": {}, "customName": "", "extendBaseMarkingAlgorithm": true, "useCustomName": false, "showCorrectAnswer": true, "showFeedbackIcon": true, "marks": 0, "gaps": [{"correctAnswerStyle": "plain", "scripts": {}, "customName": "", "precision": "2", "showFeedbackIcon": true, "showPrecisionHint": false, "customMarkingAlgorithm": "", "unitTests": [], "variableReplacements": [], "useCustomName": false, "strictPrecision": false, "correctAnswerFraction": false, "mustBeReduced": false, "precisionMessage": "

You have not given your answer to the correct precision.

", "mustBeReducedPC": 0, "maxValue": "2*a*d+b", "extendBaseMarkingAlgorithm": true, "variableReplacementStrategy": "originalfirst", "showCorrectAnswer": true, "notationStyles": ["plain", "en", "si-en"], "precisionType": "dp", "marks": 1, "precisionPartialCredit": 0, "allowFractions": false, "minValue": "2*a*d+b", "type": "numberentry"}, {"scripts": {}, "customName": "", "extendBaseMarkingAlgorithm": true, "useCustomName": false, "vsetRangePoints": 5, "showCorrectAnswer": true, "showFeedbackIcon": true, "marks": 1, "checkVariableNames": false, "answer": "2*{a}*x+{b}", "customMarkingAlgorithm": "", "checkingAccuracy": 0.001, "vsetRange": [0, 1], "unitTests": [], "failureRate": 1, "checkingType": "absdiff", "variableReplacements": [], "variableReplacementStrategy": "originalfirst", "type": "jme", "showPreview": true, "valuegenerators": [{"name": "x", "value": ""}]}], "sortAnswers": false, "customMarkingAlgorithm": "", "unitTests": [], "variableReplacements": [], "variableReplacementStrategy": "originalfirst", "type": "gapfill"}, {"prompt": "

Find the coordinates of the turning point of the function below and state whether it is a maximum or a minimum point. Give your answers to $2$ decimal places where necessary.

\n

$y=\\simplify {{f}x^2+{g}x+{h}}$

\n

Firstly, find the first and second derivatives $y$.

\n

$\\displaystyle \\frac{dy}{dx}=$ [[2]]

\n

$\\displaystyle \\frac{d^2y}{dx^2}=$ [[3]]

\n

\n

Secondly, find $x$ such that $\\displaystyle \\frac{dy}{dx}=0$.

\n

$x$-coordinate of the turning point $=$ [[0]]

\n

$y$-coordinate of the turning point $=$ [[1]]

\n

The turning point is a [[4]]

\n

\n

", "scripts": {}, "customName": "", "extendBaseMarkingAlgorithm": true, "useCustomName": false, "showCorrectAnswer": true, "showFeedbackIcon": true, "marks": 0, "gaps": [{"correctAnswerStyle": "plain", "scripts": {}, "customName": "", "precision": "2", "showFeedbackIcon": true, "showPrecisionHint": false, "customMarkingAlgorithm": "", "unitTests": [], "variableReplacements": [], "useCustomName": false, "strictPrecision": false, "correctAnswerFraction": false, "mustBeReduced": false, "precisionMessage": "

You have not given your answer to the correct precision.

", "mustBeReducedPC": 0, "maxValue": "-g/(2*f)", "extendBaseMarkingAlgorithm": true, "variableReplacementStrategy": "originalfirst", "showCorrectAnswer": true, "notationStyles": ["plain", "en", "si-en"], "precisionType": "dp", "marks": 1, "precisionPartialCredit": 0, "allowFractions": false, "minValue": "-g/(2*f)", "type": "numberentry"}, {"correctAnswerStyle": "plain", "scripts": {}, "customName": "", "precision": "2", "showFeedbackIcon": true, "showPrecisionHint": false, "customMarkingAlgorithm": "", "unitTests": [], "variableReplacements": [], "useCustomName": false, "strictPrecision": false, "correctAnswerFraction": false, "mustBeReduced": false, "precisionMessage": "

You have not given your answer to the correct precision.

", "mustBeReducedPC": 0, "maxValue": "g^2/(4*f)-g^2/(2*f)+h", "extendBaseMarkingAlgorithm": true, "variableReplacementStrategy": "originalfirst", "showCorrectAnswer": true, "notationStyles": ["plain", "en", "si-en"], "precisionType": "dp", "marks": 1, "precisionPartialCredit": 0, "allowFractions": false, "minValue": "g^2/(4*f)-g^2/(2*f)+h", "type": "numberentry"}, {"scripts": {}, "customName": "", "extendBaseMarkingAlgorithm": true, "useCustomName": false, "vsetRangePoints": 5, "showCorrectAnswer": true, "showFeedbackIcon": true, "marks": 1, "checkVariableNames": false, "answer": "2*{f}*x+{g}", "customMarkingAlgorithm": "", "checkingAccuracy": 0.001, "vsetRange": [0, 1], "unitTests": [], "failureRate": 1, "checkingType": "absdiff", "variableReplacements": [], "variableReplacementStrategy": "originalfirst", "type": "jme", "showPreview": true, "valuegenerators": [{"name": "x", "value": ""}]}, {"scripts": {}, "customName": "", "extendBaseMarkingAlgorithm": true, "useCustomName": false, "vsetRangePoints": 5, "showCorrectAnswer": true, "showFeedbackIcon": true, "marks": 1, "checkVariableNames": false, "answer": "2*{f}", "customMarkingAlgorithm": "", "checkingAccuracy": 0.001, "vsetRange": [0, 1], "unitTests": [], "failureRate": 1, "checkingType": "absdiff", "variableReplacements": [], "variableReplacementStrategy": "originalfirst", "type": "jme", "showPreview": true, "valuegenerators": []}, {"displayColumns": 0, "minMarks": 0, "scripts": {}, "showCellAnswerState": true, "matrix": ["if(maximum, 1, 0)", "if(maximum, 0, 1)"], "customName": "", "extendBaseMarkingAlgorithm": true, "useCustomName": false, "showCorrectAnswer": true, "shuffleChoices": false, "showFeedbackIcon": true, "displayType": "radiogroup", "marks": 0, "maxMarks": "0", "customMarkingAlgorithm": "", "choices": ["

maximum

", "

minimum

"], "distractors": ["", ""], "unitTests": [], "variableReplacements": [], "variableReplacementStrategy": "originalfirst", "type": "1_n_2"}], "sortAnswers": false, "customMarkingAlgorithm": "", "unitTests": [], "variableReplacements": [], "variableReplacementStrategy": "originalfirst", "type": "gapfill"}, {"prompt": "

An unpowered missile is launched vertically from the ground.

\n

At a time $t$ seconds after the instant of projection, its height, $y$ metres, above the ground is given by the formula

\n

\\[ y=\\var{z}t-\\var{w}t^2. \\]

\n

Calculate the maximum height reached by the missile.

\n

Firstly, differentiate.

\n

$\\displaystyle \\frac{dy}{dt}=$ [[0]]

\n

Now use this result and your knowledge of differentiation to find the maximum height of the missile, rounding your answer to $2$ decimal places.

\n

$y=$ [[1]]

", "scripts": {}, "customName": "", "extendBaseMarkingAlgorithm": true, "useCustomName": false, "showCorrectAnswer": true, "showFeedbackIcon": true, "marks": 0, "gaps": [{"scripts": {}, "customName": "", "extendBaseMarkingAlgorithm": true, "useCustomName": false, "vsetRangePoints": 5, "showCorrectAnswer": true, "showFeedbackIcon": true, "marks": 1, "checkVariableNames": false, "answer": "{z}-2*{w}*t", "customMarkingAlgorithm": "", "checkingAccuracy": 0.001, "vsetRange": [0, 1], "unitTests": [], "failureRate": 1, "checkingType": "absdiff", "variableReplacements": [], "variableReplacementStrategy": "originalfirst", "type": "jme", "showPreview": true, "valuegenerators": [{"name": "t", "value": ""}]}, {"correctAnswerStyle": "plain", "scripts": {}, "customName": "", "precision": "2", "showFeedbackIcon": true, "showPrecisionHint": false, "customMarkingAlgorithm": "", "unitTests": [], "variableReplacements": [], "useCustomName": false, "strictPrecision": false, "correctAnswerFraction": false, "mustBeReduced": false, "precisionMessage": "You have not given your answer to the correct precision.", "mustBeReducedPC": 0, "maxValue": "z^2/(4w)", "extendBaseMarkingAlgorithm": true, "variableReplacementStrategy": "originalfirst", "showCorrectAnswer": true, "notationStyles": ["plain", "en", "si-en"], "precisionType": "dp", "marks": 1, "precisionPartialCredit": 0, "allowFractions": false, "minValue": "z^2/(4w)", "type": "numberentry"}], "sortAnswers": false, "customMarkingAlgorithm": "", "unitTests": [], "variableReplacements": [], "variableReplacementStrategy": "originalfirst", "type": "gapfill"}], "type": "question", "contributors": [{"name": "Christian Lawson-Perfect", "profile_url": "https://numbas.mathcentre.ac.uk/accounts/profile/7/"}, {"name": "Vicky Hall", "profile_url": "https://numbas.mathcentre.ac.uk/accounts/profile/659/"}]}]}], "contributors": [{"name": "Christian Lawson-Perfect", "profile_url": "https://numbas.mathcentre.ac.uk/accounts/profile/7/"}, {"name": "Vicky Hall", "profile_url": "https://numbas.mathcentre.ac.uk/accounts/profile/659/"}]}