CAIE P2 2024 March — Question 3 7 marks

Exam BoardCAIE
ModuleP2 (Pure Mathematics 2)
Year2024
SessionMarch
Marks7
PaperDownload PDF ↗
Mark schemeDownload PDF ↗
TopicFactor & Remainder Theorem
TypeVerify, factorise, solve with substitution
DifficultyModerate -0.3 This is a straightforward application of the factor theorem requiring students to substitute x=1/2 to find a, then perform polynomial division or comparison of coefficients to complete the factorization. Part (b) adds a minor twist by requiring substitution of cos θ and solving basic trigonometric equations. The question is slightly easier than average as it's a standard textbook exercise with clear signposting and routine techniques, though the two-part structure and trig element prevent it from being significantly below average.
Spec1.02f Solve quadratic equations: including in a function of unknown1.02j Manipulate polynomials: expanding, factorising, division, factor theorem

The polynomial \(\mathrm{p}(x)\) is defined by $$\mathrm{p}(x) = 6x^3 + ax^2 + 3x - 10,$$ where \(a\) is a constant. It is given that \((2x - 1)\) is a factor of \(\mathrm{p}(x)\).
  1. Find the value of \(a\) and hence factorise \(\mathrm{p}(x)\) completely. [5]
  2. Solve the equation \(\mathrm{p}(\cos\theta) = 0\) for \(-90° < \theta < 90°\). [2]

Question 3:

AnswerMarks Guidance
3(a)Substitute x=1, equate to zero and attempt solution
2M1
Obtain a=31A1
Divide by 2x−1 at least as far as 3x2 +mxM1 Or equivalent (for example by inspection, …).
Obtain 3x2 +17x+10A1
Obtain (2x−1)(3x+2)(x+5)A1
5

AnswerMarks Guidance
3(b)Attempt solution of sin=k where k is valid constant from answer to part (a) M1
Obtain −11.5A1 Or greater accuracy.
2
AnswerMarks Guidance
QuestionAnswer Marks
Question 3:
--- 3(a) ---
3(a) | Substitute x=1, equate to zero and attempt solution
2 | M1
Obtain a=31 | A1
Divide by 2x−1 at least as far as 3x2 +mx | M1 | Or equivalent (for example by inspection, …).
Obtain 3x2 +17x+10 | A1
Obtain (2x−1)(3x+2)(x+5) | A1
5
--- 3(b) ---
3(b) | Attempt solution of sin=k where k is valid constant from answer to part (a) | M1
Obtain −11.5 | A1 | Or greater accuracy.
2
Question | Answer | Marks | Guidance
The polynomial $\mathrm{p}(x)$ is defined by
$$\mathrm{p}(x) = 6x^3 + ax^2 + 3x - 10,$$
where $a$ is a constant. It is given that $(2x - 1)$ is a factor of $\mathrm{p}(x)$.

\begin{enumerate}[label=(\alph*)]
\item Find the value of $a$ and hence factorise $\mathrm{p}(x)$ completely. [5]
\item Solve the equation $\mathrm{p}(\cos\theta) = 0$ for $-90° < \theta < 90°$. [2]
\end{enumerate}

\hfill \mbox{\textit{CAIE P2 2024 Q3 [7]}}