OCR MEI AS Paper 2 2018 June — Question 10 9 marks

Exam BoardOCR MEI
ModuleAS Paper 2 (AS Paper 2)
Year2018
SessionJune
Marks9
PaperDownload PDF ↗
Mark schemeDownload PDF ↗
TopicTangents, normals and gradients
TypeDetermine nature of stationary points
DifficultyModerate -0.8 This is a straightforward calculus question requiring standard differentiation of power functions, finding stationary points by setting dy/dx = 0, and using the second derivative test. All techniques are routine AS-level procedures with no problem-solving insight needed, making it easier than average but not trivial due to the algebraic manipulation required.
Spec1.07d Second derivatives: d^2y/dx^2 notation1.07l Derivative of ln(x): and related functions1.07n Stationary points: find maxima, minima using derivatives1.07p Points of inflection: using second derivative

  1. A curve has equation \(y = 16x + \frac{1}{x}\). Find
    1. \(\frac{dy}{dx}\), [2]
    2. \(\frac{d^2y}{dx^2}\). [2]
  2. Hence

Question 10:
AnswerMarks Guidance
10(i) (A)
16 oe
AnswerMarks
x3M1
A1
AnswerMarks
[2]1.1
1.1One term correct
(B)kx ‒ 3 ‒ 1
6
6x ‒ 4 or
AnswerMarks
x4M1
A1
AnswerMarks
[2]1.1
1.1dy
FT their for M1
dx
AnswerMarks Guidance
10(ii) dy
their = 0
dx
x = ½
y = 12
substitution of their x = ½ in their second
derivative
AnswerMarks
[96 ] which is positive so (½, 12) is a minimumM1
A1
A1
M1
A1
AnswerMarks
[5]2.1
1.1
1.1
1.1
AnswerMarks
2.4FT their x; dependent on (i)(B)
involving x
www
Question 10:
10 | (i) | (A) | 2
16 oe
x3 | M1
A1
[2] | 1.1
1.1 | One term correct
(B) | kx ‒ 3 ‒ 1
6
6x ‒ 4 or
x4 | M1
A1
[2] | 1.1
1.1 | dy
FT their for M1
dx
10 | (ii) | dy
their = 0
dx
x = ½
y = 12
substitution of their x = ½ in their second
derivative
[96 ] which is positive so (½, 12) is a minimum | M1
A1
A1
M1
A1
[5] | 2.1
1.1
1.1
1.1
2.4 | FT their x; dependent on (i)(B)
involving x
www
\begin{enumerate}[label=(\roman*)]
\item A curve has equation $y = 16x + \frac{1}{x}$. Find

\begin{enumerate}[label=(\Alph*)]
\item $\frac{dy}{dx}$, [2]

\item $\frac{d^2y}{dx^2}$. [2]
\end{enumerate}

\item Hence
\begin{itemize}
\item find the coordinates of the stationary point,
\item determine the nature of the stationary point. [5]
\end{itemize}
\end{enumerate}

\hfill \mbox{\textit{OCR MEI AS Paper 2 2018 Q10 [9]}}