Find stationary points

Use calculus to find coordinates of stationary points by solving dy/dx = 0.

114 questions

OCR Mechanics 1 2018 March Q5
5 In this question you must show detailed reasoning.
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The function f is defined for the domain \(x \geqslant 0\) by $$\mathrm { f } ( x ) = \left( 2 x ^ { 2 } - 3 x \right) \mathrm { e } ^ { - x }$$ The diagram shows the curve \(y = \mathrm { f } ( x )\).
  1. Find the range of f.
  2. The function g is defined for the domain \(x \geqslant k\) by $$\mathrm { g } ( x ) = \left( 2 x ^ { 2 } - 3 x \right) \mathrm { e } ^ { - x } .$$ Given that g is a one-one function, state the least possible value of \(k\).
  3. Find the exact area of the shaded region enclosed by the curve and the \(x\)-axis.
  4. Determine the values of \(p\) and \(q\) for which $$x ^ { 2 } - 6 x + 10 \equiv ( x - p ) ^ { 2 } + q .$$
  5. Use the substitution \(x - p = \tan u\), where \(p\) takes the value found in part (i), to evaluate $$\int _ { 3 } ^ { 4 } \frac { 1 } { x ^ { 2 } - 6 x + 10 } \mathrm {~d} x .$$
  6. Determine the value of $$\int _ { 3 } ^ { 4 } \frac { x } { x ^ { 2 } - 6 x + 10 } \mathrm {~d} x$$ giving your answer in the form \(a + \ln b\), where \(a\) and \(b\) are constants to be determined.
OCR Mechanics 1 2018 September Q2
2 A curve has equation \(y = a x ^ { 4 } + b x ^ { 3 } - 2 x + 3\).
  1. Given that the curve has a stationary point where \(x = 2\), show that \(16 a + 6 b = 1\).
  2. Given also that this stationary point is a point of inflection, determine the values of \(a\) and \(b\).
OCR AS Pure 2017 Specimen Q4
4 The curve \(y = 2 x ^ { 3 } + 3 x ^ { 2 } - k x + 4\) has a stationary point where \(x = 2\).
  1. Determine the value of the constant \(k\).
  2. Determine whether this stationary point is a maximum or a minimum point.
AQA C1 2008 January Q2
2 The curve with equation \(y = x ^ { 4 } - 32 x + 5\) has a single stationary point, \(M\).
  1. Find \(\frac { \mathrm { d } y } { \mathrm {~d} x }\).
  2. Hence find the \(x\)-coordinate of \(M\).
    1. Find \(\frac { \mathrm { d } ^ { 2 } y } { \mathrm {~d} x ^ { 2 } }\).
    2. Hence, or otherwise, determine whether \(M\) is a maximum or a minimum point.
  3. Determine whether the curve is increasing or decreasing at the point on the curve where \(x = 0\).
OCR MEI C2 2010 June Q3
3
  1. Differentiate \(x ^ { 3 } - 6 x ^ { 2 } - 15 x + 50\).
  2. Hence find the \(x\)-coordinates of the stationary points on the curve \(y = x ^ { 3 } - 6 x ^ { 2 } - 15 x + 50\).
OCR MEI FP3 2015 June Q2
2 A surface has equation \(z = 3 x ^ { 2 } - 12 x y + 2 y ^ { 3 } + 60\).
  1. Show that the point \(\mathrm { A } ( 8,4 , - 4 )\) is a stationary point on the surface. Find the coordinates of the other stationary point, B , on this surface.
  2. A point P with coordinates \(( 8 + h , 4 + k , p )\) lies on the surface.
    (A) Show that \(p = - 4 + 3 ( h - 2 k ) ^ { 2 } + 2 k ^ { 2 } ( 6 + k )\).
    (B) Deduce that the stationary point A is a local minimum.
    (C) By considering sections of the surface near to B in each of the planes \(x = 0\) and \(y = 0\), investigate the nature of the stationary point B .
  3. The point Q with coordinates \(( 1,1,53 )\) lies on the surface. Show that the equation of the tangent plane at Q is $$6 x + 6 y + z = 65$$
  4. The tangent plane at the point R has equation \(6 x + 6 y + z = \lambda\) where \(\lambda \neq 65\). Find the coordinates of R .
OCR H240/03 Q6
6 A curve has equation \(y = x ^ { 2 } + k x - 4 x ^ { - 1 }\) where \(k\) is a constant. Given that the curve has a minimum point when \(x = - 2\)
  • find the value of \(k\)
  • show that the curve has a point of inflection which is not a stationary point.
AQA AS Paper 1 2019 June Q8
8 Prove that the curve with equation $$y = 2 x ^ { 5 } + 5 x ^ { 4 } + 10 x ^ { 3 } - 8$$ has only one stationary point, stating its coordinates.
AQA AS Paper 1 2022 June Q8
4 marks
8 A curve has equation $$y = x ^ { 3 } - 6 x + \frac { 9 } { x }$$ 8
  1. Show that the \(x\) coordinates of the stationary points of the curve satisfy the equation $$x ^ { 4 } - 2 x ^ { 2 } - 3 = 0$$ 8
  2. Deduce that the curve has exactly two stationary points.
    8
  3. Find the coordinates and nature of the two stationary points. Fully justify your answer.
    [0pt] [4 marks]
    8
  4. Write down the equation of a line which is a tangent to the curve in two places.
AQA AS Paper 2 2019 June Q9
9
  1. Find the exact coordinates of the turning points of \(C\).
    Determine the nature of each turning point.
    Fully justify your answer.
    9
  2. State the coordinates of the turning points of the curve $$y = \mathrm { f } ( x + 1 ) - 4$$
AQA AS Paper 2 2020 June Q10
10 A curve has gradient function $$\frac { \mathrm { d } y } { \mathrm {~d} x } = 3 x ^ { 2 } - 12 x + c$$ The curve has a turning point at ( \(- 1,1\) )
10
  1. Find the coordinates of the other turning point of the curve.
    Fully justify your answer.
    10
  2. Find the set of values of \(x\) for which \(y\) is increasing.
AQA AS Paper 2 2024 June Q8
5 marks
8 Prove that the graph of the curve with equation $$y = x ^ { 3 } + 15 x - \frac { 18 } { x }$$ has no stationary points.
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AQA AS Paper 2 Specimen Q4
3 marks
4 Find the coordinates, in terms of \(a\), of the minimum point on the curve \(y = x ^ { 2 } - 5 x + a\), where \(a\) is a constant. Fully justify your answer.
[0pt] [3 marks]
SPS SPS FM 2024 November Q14
14 November 2024 Instructions
  • Answer all the questions.
  • Use black or blue ink. Pencil may be used for graphs and diagrams only.
  • There are blank pages at the end of the paper for additional working. You must clearly indicate when you have moved onto additional pages on the question itself. Make sure to include the question number.
  • You are permitted to use a scientific or graphical calculator in this paper.
  • Where appropriate, your answer should be supported with working. Marks might be given for using a correct method, even if your answer is wrong.
  • Give non-exact numerical answers correct to 3 significant figures unless a different degree of accuracy is specified in the question.
  • The acceleration due to gravity is denoted by \(g \mathrm {~ms} ^ { - 2 }\). When a numerical value is needed use \(g = 9.8\) unless a different value is specified in the question.
Information
  • The total mark for this paper is \(\mathbf { 6 1 }\) marks.
  • The marks for each question are shown in brackets.
  • You are reminded of the need for clear presentation in your answers.
  • You have \(\mathbf { 6 0 }\) minutes for this paper.
\section*{Arithmetic series} \(S _ { n } = \frac { 1 } { 2 } n ( a + l ) = \frac { 1 } { 2 } n \{ 2 a + ( n - 1 ) d \}\) \section*{Geometric series} \(S _ { n } = \frac { a \left( 1 - r ^ { n } \right) } { 1 - r }\)
\(S _ { \infty } = \frac { a } { 1 - r }\) for \(| r | < 1\) \section*{Binomial series} \(( a + b ) ^ { n } = a ^ { n } + { } ^ { n } \mathrm { C } _ { 1 } a ^ { n - 1 } b + { } ^ { n } \mathrm { C } _ { 2 } a ^ { n - 2 } b ^ { 2 } + \ldots + { } ^ { n } \mathrm { C } _ { r } a ^ { n - r } b ^ { r } + \ldots + b ^ { n } \quad ( n \in \mathbb { N } )\),
where \({ } ^ { n } \mathrm { C } _ { r } = { } _ { n } \mathrm { C } _ { r } = \binom { n } { r } = \frac { n ! } { r ! ( n - r ) ! }\)
\(( 1 + x ) ^ { n } = 1 + n x + \frac { n ( n - 1 ) } { 2 ! } x ^ { 2 } + \ldots + \frac { n ( n - 1 ) \ldots ( n - r + 1 ) } { r ! } x ^ { r } + \ldots \quad ( | x | < 1 , n \in \mathbb { R } )\) \section*{Series} \(\sum _ { r = 1 } ^ { n } r ^ { 2 } = \frac { 1 } { 6 } n ( n + 1 ) ( 2 n + 1 ) , \sum _ { r = 1 } ^ { n } r ^ { 3 } = \frac { 1 } { 4 } n ^ { 2 } ( n + 1 ) ^ { 2 }\) \section*{Maclaurin series} \(\mathrm { f } ( x ) = \mathrm { f } ( 0 ) + \mathrm { f } ^ { \prime } ( 0 ) x + \frac { \mathrm { f } ^ { \prime \prime } ( 0 ) } { 2 ! } x ^ { 2 } + \ldots + \frac { \mathrm { f } ^ { ( r ) } ( 0 ) } { r ! } x ^ { r } + \ldots\)
\(\mathrm { e } ^ { x } = \exp ( x ) = 1 + x + \frac { x ^ { 2 } } { 2 ! } + \ldots + \frac { x ^ { r } } { r ! } + \ldots\) for all \(x\)
\(\ln ( 1 + x ) = x - \frac { x ^ { 2 } } { 2 } + \frac { x ^ { 3 } } { 3 } - \ldots + ( - 1 ) ^ { r + 1 } \frac { x ^ { r } } { r } + \ldots ( - 1 < x \leq 1 )\)
\(\sin x = x - \frac { x ^ { 3 } } { 3 ! } + \frac { x ^ { 5 } } { 5 ! } - \ldots + ( - 1 ) ^ { r } \frac { x ^ { 2 r + 1 } } { ( 2 r + 1 ) ! } + \ldots\) for all \(x\)
\(\cos x = 1 - \frac { x ^ { 2 } } { 2 ! } + \frac { x ^ { 4 } } { 4 ! } - \ldots + ( - 1 ) ^ { r } \frac { x ^ { 2 r } } { ( 2 r ) ! } + \ldots\) for all \(x\)
\(( 1 + x ) ^ { n } = 1 + n x + \frac { n ( n - 1 ) } { 2 ! } x ^ { 2 } + \ldots + \frac { n ( n - 1 ) \ldots ( n - r + 1 ) } { r ! } x ^ { r } + \ldots \quad ( | x | < 1 , n \in \mathbb { R } )\) \section*{Differentiation}
\(\mathrm { f } ( x )\)\(\mathrm { f } ^ { \prime } ( x )\)
\(\tan k x\)\(k \sec ^ { 2 } k x\)
\(\sec x\)\(\sec x \tan x\)
\(\cot x\)\(- \operatorname { cosec } ^ { 2 } x\)
\(\operatorname { cosec } x\)\(- \operatorname { cosec } x \cot x\)
\(\arcsin x\) or \(\sin ^ { - 1 } x\)\(\frac { 1 } { \sqrt { 1 - x ^ { 2 } } }\)
\(\arccos x\) or \(\cos ^ { - 1 } x\)\(- \frac { 1 } { \sqrt { 1 - x ^ { 2 } } }\)
\(\arctan x\) or \(\tan ^ { - 1 } x\)\(\frac { 1 } { 1 + x ^ { 2 } }\)
Quotient rule \(y = \frac { u } { v } , \frac { \mathrm {~d} y } { \mathrm {~d} x } = \frac { v \frac { \mathrm {~d} u } { \mathrm {~d} x } - u \frac { \mathrm {~d} v } { \mathrm {~d} x } } { v ^ { 2 } }\) \section*{Differentiation from first principles} \(\mathrm { f } ^ { \prime } ( x ) = \lim _ { h \rightarrow 0 } \frac { \mathrm { f } ( x + h ) - \mathrm { f } ( x ) } { h }\) \section*{Integration} \(\int \frac { \mathrm { f } ^ { \prime } ( x ) } { \mathrm { f } ( x ) } \mathrm { d } x = \ln | \mathrm { f } ( x ) | + c\)
\(\int \mathrm { f } ^ { \prime } ( x ) ( \mathrm { f } ( x ) ) ^ { n } \mathrm {~d} x = \frac { 1 } { n + 1 } ( \mathrm { f } ( x ) ) ^ { n + 1 } + c\)
Integration by parts \(\int u \frac { \mathrm {~d} v } { \mathrm {~d} x } \mathrm {~d} x = u v - \int v \frac { \mathrm {~d} u } { \mathrm {~d} x } \mathrm {~d} x\) The mean value of \(\mathrm { f } ( x )\) on the interval \([ a , b ]\) is \(\frac { 1 } { b - a } \int _ { a } ^ { b } \mathrm { f } ( x ) \mathrm { d } x\)
Area of sector enclosed by polar curve is \(\frac { 1 } { 2 } \int r ^ { 2 } \mathrm {~d} \theta\)
\(\mathrm { f } ( x )\)\(\int \mathrm { f } ( x ) \mathrm { d } x\)
\(\frac { 1 } { \sqrt { a ^ { 2 } - x ^ { 2 } } }\)\(\sin ^ { - 1 } \left( \frac { x } { a } \right) \quad ( | x | < a )\)
\(\frac { 1 } { a ^ { 2 } + x ^ { 2 } }\)\(\frac { 1 } { a } \tan ^ { - 1 } \left( \frac { x } { a } \right)\)
\(\frac { 1 } { \sqrt { a ^ { 2 } + x ^ { 2 } } }\)\(\sinh ^ { - 1 } \left( \frac { x } { a } \right)\) or \(\ln \left( x + \sqrt { x ^ { 2 } + a ^ { 2 } } \right)\)
\(\frac { 1 } { \sqrt { x ^ { 2 } - a ^ { 2 } } }\)\(\cosh ^ { - 1 } \left( \frac { x } { a } \right)\) or \(\ln \left( x + \sqrt { x ^ { 2 } - a ^ { 2 } } \right) \quad ( x > a )\)
\section*{Numerical methods} Trapezium rule: \(\int _ { a } ^ { b } y \mathrm {~d} x \approx \frac { 1 } { 2 } h \left\{ \left( y _ { 0 } + y _ { n } \right) + 2 \left( y _ { 1 } + y _ { 2 } + \ldots + y _ { n - 1 } \right) \right\}\), where \(h = \frac { b - a } { n }\)
The Newton-Raphson iteration for solving \(\mathrm { f } ( x ) = 0 : x _ { n + 1 } = x _ { n } - \frac { \mathrm { f } \left( x _ { n } \right) } { \mathrm { f } ^ { \prime } \left( x _ { n } \right) }\) \section*{Complex numbers} Circles: \(| z - a | = k\)
Half lines: \(\arg ( z - a ) = \alpha\)
Lines: \(| z - a | = | z - b |\) \section*{Small angle approximations} \(\sin \theta \approx \theta , \cos \theta \approx 1 - \frac { 1 } { 2 } \theta ^ { 2 } , \tan \theta \approx \theta\) where \(\theta\) is small and measured in radians \section*{Trigonometric identities} \(\sin ( A \pm B ) = \sin A \cos B \pm \cos A \sin B\)
\(\cos ( A \pm B ) = \cos A \cos B \mp \sin A \sin B\)
\(\tan ( A \pm B ) = \frac { \tan A \pm \tan B } { 1 \mp \tan A \tan B } \quad \left( A \pm B \neq \left( k + \frac { 1 } { 2 } \right) \pi \right)\) \section*{Hyperbolic functions} \(\cosh ^ { 2 } x - \sinh ^ { 2 } x = 1\)
\(\sinh ^ { - 1 } x = \ln \left[ x + \sqrt { \left( x ^ { 2 } + 1 \right) } \right]\)
\(\cosh ^ { - 1 } x = \ln \left[ x + \sqrt { \left( x ^ { 2 } - 1 \right) } \right] , x \geq 1\)
\(\tanh ^ { - 1 } x = \frac { 1 } { 2 } \ln \left( \frac { 1 + x } { 1 - x } \right) , - 1 < x < 1\)
  1. In this question you must show all stages of your working. Solutions relying entirely on calculator technology are not acceptable.
Determine the values of \(x\) for which $$64 \cosh ^ { 4 } x - 64 \sinh ^ { 2 } x - 73 = 0$$ Give your answer in the form \(q \ln 2\) where \(q\) is rational and in simplest form.
2. (a) Prove that $$\tanh ^ { - 1 } ( x ) = \frac { 1 } { 2 } \ln \left( \frac { 1 + x } { 1 - x } \right) \quad - k < x < k$$ stating the value of the constant \(k\).
(b) Hence, or otherwise, solve the equation $$2 x = \tanh ( \ln \sqrt { 2 - 3 x } )$$ [BLANK PAGE]
3. In this question you must show detailed reasoning. The roots of the equation \(x ^ { 3 } - x ^ { 2 } + k x - 2 = 0\) are \(\alpha , \frac { 1 } { \alpha }\) and \(\beta\).
(a) Evaluate, in exact form, the roots of the equation.
(b) Find \(k\).
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4. (a) (i) Given that \(f ( x ) = \sqrt { 1 + 2 x }\), find \(f ^ { \prime } ( x )\) and \(f ^ { \prime \prime } ( x )\).
(ii) Hence, find the first three terms of the Maclaurin series for \(\sqrt { 1 + 2 x }\).
(b) Hence, using a suitable value for \(x\), show that \(\sqrt { 5 } \approx \frac { 143 } { 64 }\).
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5. In this question you must show detailed reasoning.
(i) Given that $$z _ { 1 } = 6 \left( \cos \left( \frac { \pi } { 3 } \right) + i \sin \left( \frac { \pi } { 3 } \right) \right) \quad \text { and } \quad z _ { 2 } = 6 \sqrt { 3 } \left( \cos \left( \frac { 5 \pi } { 6 } \right) + i \sin \left( \frac { 5 \pi } { 6 } \right) \right)$$ show that $$z _ { 1 } + z _ { 2 } = 12 \left( \cos \left( \frac { 2 \pi } { 3 } \right) + i \sin \left( \frac { 2 \pi } { 3 } \right) \right)$$ (ii) Given that $$\arg ( z - 5 ) = \frac { 2 \pi } { 3 }$$ determine the least value of \(| \boldsymbol { z } |\) as \(Z\) varies.
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6. A curve has polar equation \(r = a ( \cos \theta + 2 \sin \theta )\), where \(a\) is a positive constant and \(0 \leq \theta \leq \pi\).
(a) Determine the polar coordinates of the point on the curve which is furthest from the pole.
(b) (i) Show that the curve is a circle whose radius should be specified.
(ii) Write down the polar coordinates of the centre of the circle.
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7. (a) It is conjectured that $$\frac { 1 } { 2 ! } + \frac { 2 } { 3 ! } + \frac { 3 } { 4 ! } + \ldots + \frac { n - 1 } { n ! } = a - \frac { b } { n ! }$$ where \(a\) and \(b\) are constants, and \(n\) is an integer such that \(n \geq 2\). By considering particular cases, show that if the conjecture is correct then $$a = b = 1$$ (b) Use induction to prove that, for \(n \geq 2\), the following is true $$\frac { 1 } { 2 ! } + \frac { 2 } { 3 ! } + \frac { 3 } { 4 ! } + \ldots + \frac { n - 1 } { n ! } = 1 - \frac { 1 } { n ! }$$ [BLANK PAGE]
8. (a) Use standard results for \(\sum _ { r = 1 } ^ { n } r ^ { 2 }\) and \(\sum _ { r = 1 } ^ { n } r\) to show that $$\sum _ { r = 1 } ^ { n } ( 3 r - 2 ) ^ { 2 } = \frac { 1 } { 2 } n \left[ 6 n ^ { 2 } - 3 n - 1 \right]$$ for all positive integers \(n\).
(b) Hence find any values of \(n\) for which $$\sum _ { r = 5 } ^ { n } ( 3 r - 2 ) ^ { 2 } + 103 \sum _ { r = 1 } ^ { 28 } r \cos \left( \frac { r \pi } { 2 } \right) = 3 n ^ { 3 }$$ [BLANK PAGE]
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