CAIE Further Paper 2 2020 June — Question 5 9 marks

Exam BoardCAIE
ModuleFurther Paper 2 (Further Paper 2)
Year2020
SessionJune
Marks9
PaperDownload PDF ↗
Mark schemeDownload PDF ↗
TopicParametric differentiation
TypeFind second derivative d²y/dx²
DifficultyChallenging +1.3 This is a standard Further Maths parametric calculus question requiring arc length integration and second derivative calculation. Part (a) involves computing √((dx/dt)² + (dy/dt)²) which simplifies nicely to |t + 1/t|, leading to a straightforward integration. Part (b) requires the chain rule for d²y/dx² = d/dx(dy/dx) = (d/dt(dy/dx))/(dx/dt), involving routine algebraic manipulation. While requiring multiple techniques and careful algebra, these are well-practiced procedures for Further Maths students with no novel problem-solving insight needed.
Spec1.07s Parametric and implicit differentiation4.08d Volumes of revolution: about x and y axes

The curve \(C\) has parametric equations $$x = \frac{1}{2}t^2 - \ln t, \quad y = 2t + 1, \quad \text{for } \frac{1}{2} \leqslant t \leqslant 2.$$
  1. Find the exact length of \(C\). [5]
  2. Find \(\frac{d^2y}{dx^2}\) in terms of \(t\), simplifying your answer. [4]

Question 5:
AnswerMarks
5Where a candidate has misread a number in the question and used that value consistently throughout, provided that number does not alter the difficulty or
the method required, award all marks earned and deduct just 1 mark for the misread.

AnswerMarks
5(a)x= − −1, y=
t t 2B1
( )
AnswerMarks
x2+y2 =t2−2+t −2+4= t+t −1 2M1 A1
 2 t+t−1dt = 1t2 +lnt 2 = 15 +2ln2
1 2  1 8
AnswerMarks
2 2M1 A1
5
AnswerMarks Guidance
QuestionAnswer Marks

AnswerMarks
5(b)dy y 2
= =
AnswerMarks
dx x t−t−1B1
( )
−2 1+t−2
d  2 
=
AnswerMarks
dt  t−t−1   ( t−t−1 )2B1
( )
−2 1+t−2
d2y d  2  dt
= × =
AnswerMarks
dx2 dt  t−t−1   dx ( t −t−1 )3M1 A1
4
AnswerMarks Guidance
QuestionAnswer Marks
Question 5:
5 | Where a candidate has misread a number in the question and used that value consistently throughout, provided that number does not alter the difficulty or
the method required, award all marks earned and deduct just 1 mark for the misread.
--- 5(a) ---
5(a) | x= − −1, y=
t t 2 | B1
( )
x2+y2 =t2−2+t −2+4= t+t −1 2 | M1 A1
 2 t+t−1dt = 1t2 +lnt 2 = 15 +2ln2
1 2  1 8
2 2 | M1 A1
5
Question | Answer | Marks
--- 5(b) ---
5(b) | dy y 2
= =
dx x t−t−1 | B1
( )
−2 1+t−2
d  2 
=
dt  t−t−1   ( t−t−1 )2 | B1
( )
−2 1+t−2
d2y d  2  dt
= × =
dx2 dt  t−t−1   dx ( t −t−1 )3 | M1 A1
4
Question | Answer | Marks
The curve $C$ has parametric equations
$$x = \frac{1}{2}t^2 - \ln t, \quad y = 2t + 1, \quad \text{for } \frac{1}{2} \leqslant t \leqslant 2.$$

\begin{enumerate}[label=(\alph*)]
\item Find the exact length of $C$. [5]

\item Find $\frac{d^2y}{dx^2}$ in terms of $t$, simplifying your answer. [4]
\end{enumerate}

\hfill \mbox{\textit{CAIE Further Paper 2 2020 Q5 [9]}}