CAIE P1 2024 November — Question 10 10 marks

Exam BoardCAIE
ModuleP1 (Pure Mathematics 1)
Year2024
SessionNovember
Marks10
PaperDownload PDF ↗
Mark schemeDownload PDF ↗
TopicDifferentiating Transcendental Functions
TypeFind normal line equation
DifficultyStandard +0.3 This is a straightforward multi-part question testing standard A-level calculus techniques: finding a normal line (gradient calculation), integration with fractional powers, and analyzing whether a function is increasing/decreasing using the discriminant. All parts follow routine procedures with no novel problem-solving required, making it slightly easier than average.
Spec1.07i Differentiate x^n: for rational n and sums1.07m Tangents and normals: gradient and equations1.07n Stationary points: find maxima, minima using derivatives1.07o Increasing/decreasing: functions using sign of dy/dx1.08b Integrate x^n: where n != -1 and sums1.08c Integrate e^(kx), 1/x, sin(kx), cos(kx)

A function f with domain \(x > 0\) is such that \(\mathrm{f}'(x) = 8(2x - 3)^{\frac{1}{3}} - 10x^{\frac{3}{5}}\). It is given that the curve with equation \(y = \mathrm{f}(x)\) passes through the point \((1, 0)\).
  1. Find the equation of the normal to the curve at the point \((1, 0)\). [3]
  2. Find f\((x)\). [4]
It is given that the equation \(\mathrm{f}'(x) = 0\) can be expressed in the form $$125x^2 - 128x + 192 = 0.$$
  1. Determine, making your reasoning clear, whether f is an increasing function, a decreasing function or neither. [3]

Question 10:

AnswerMarks Guidance
10(a)−18 B1
1
AnswerMarks Guidance
18M1 Use of m m =−1from f(x) with x=1.
1 2
y − 0  1
=
AnswerMarks Guidance
x−1 18A1 OE
ISW
3
AnswerMarks Guidance
QuestionAnswer Marks

AnswerMarks
10(b)   
 4 1 1  5 1
 f(x)=  8(2x−3) 3. .  −10x3.  +c
 2 4   5 
 3  3
 4 5 
3(2x−3) 3 −6x3 +c
AnswerMarks Guidance
 B1B1 B1 for each unsimplified {}.
Can be implied by equivalent simplified or partly simplified
versions.
4 5
AnswerMarks Guidance
0=3 ( 2(1)−3 ) 3 −6(1) 3 +c  0=3−6+cM1 Use of x=1 and y=0 in their integrated f(x), defined as an
expression with at least one correct power, which must contain
+ c.
4 5
AnswerMarks Guidance
  f (x) or y=  3(2x−3) 3 −6x3 +3A1 Only condone c = 3 as their final answer if all coefficients have
previously been simplified in a correct statement.
4

AnswerMarks
10(c)b2 −4ac=1282 −4125192 and stating “< 0”
OR use of the quadratic formula and stating “No solutions”
OR completing the square for the given quadratic and stating positive or > 0.
AnswerMarks Guidance
OR sketch of the given quadratic and stating positive.M1* b2 −4ac=−79616 can be accepted in place of working.
No turning points [in the original function.]DM1
Decreasing because f(any positive x value)0A1 WWW
e.g. f'(1)=−18.
3
Question 10:
--- 10(a) ---
10(a) | −18 | B1 | SOI
1
18 | M1 | Use of m m =−1from f(x) with x=1.
1 2
y − 0  1
=
x−1 18 | A1 | OE
ISW
3
Question | Answer | Marks | Guidance
--- 10(b) ---
10(b) |    
 4 1 1  5 1
 f(x)=  8(2x−3) 3. .  −10x3.  +c
 2 4   5 
 3  3
 4 5 
3(2x−3) 3 −6x3 +c
  | B1B1 | B1 for each unsimplified {}.
Can be implied by equivalent simplified or partly simplified
versions.
4 5
0=3 ( 2(1)−3 ) 3 −6(1) 3 +c  0=3−6+c | M1 | Use of x=1 and y=0 in their integrated f(x), defined as an
expression with at least one correct power, which must contain
+ c.
4 5
  f (x) or y=  3(2x−3) 3 −6x3 +3 | A1 | Only condone c = 3 as their final answer if all coefficients have
previously been simplified in a correct statement.
4
--- 10(c) ---
10(c) | b2 −4ac=1282 −4125192 and stating “< 0”
OR use of the quadratic formula and stating “No solutions”
OR completing the square for the given quadratic and stating positive or > 0.
OR sketch of the given quadratic and stating positive. | M1* | b2 −4ac=−79616 can be accepted in place of working.
No turning points [in the original function.] | DM1
Decreasing because f(any positive x value)0 | A1 | WWW
e.g. f'(1)=−18.
3
A function f with domain $x > 0$ is such that $\mathrm{f}'(x) = 8(2x - 3)^{\frac{1}{3}} - 10x^{\frac{3}{5}}$. It is given that the curve with equation $y = \mathrm{f}(x)$ passes through the point $(1, 0)$.

\begin{enumerate}[label=(\alph*)]
\item Find the equation of the normal to the curve at the point $(1, 0)$. [3]

\item Find f$(x)$. [4]
\end{enumerate}

It is given that the equation $\mathrm{f}'(x) = 0$ can be expressed in the form
$$125x^2 - 128x + 192 = 0.$$

\begin{enumerate}[label=(\alph*)]
\setcounter{enumi}{2}
\item Determine, making your reasoning clear, whether f is an increasing function, a decreasing function or neither. [3]
\end{enumerate}

\hfill \mbox{\textit{CAIE P1 2024 Q10 [10]}}