OCR C2 — Question 5 8 marks

Exam BoardOCR
ModuleC2 (Core Mathematics 2)
Marks8
PaperDownload PDF ↗
Mark schemeDownload PDF ↗
TopicFactor & Remainder Theorem
TypeSingle polynomial, two remainder/factor conditions
DifficultyModerate -0.3 This is a standard C2 polynomial question testing factor theorem and remainder theorem. Part (i) requires setting up two simultaneous equations from given conditions (routine application of theorems), and part (ii) involves verification and factorisation using the found root. The algebraic manipulation is straightforward with no conceptual challenges beyond direct application of learned techniques.
Spec1.02j Manipulate polynomials: expanding, factorising, division, factor theorem

The cubic polynomial \(f(x)\) is given by $$f(x) = x^3 + ax + b,$$ where \(a\) and \(b\) are constants. It is given that \((x + 1)\) is a factor of \(f(x)\) and that the remainder when \(f(x)\) is divided by \((x - 3)\) is 16.
  1. Find the values of \(a\) and \(b\). [5]
  2. Hence verify that \(f(2) = 0\), and factorise \(f(x)\) completely. [3]

The cubic polynomial $f(x)$ is given by
$$f(x) = x^3 + ax + b,$$
where $a$ and $b$ are constants. It is given that $(x + 1)$ is a factor of $f(x)$ and that the remainder when $f(x)$ is divided by $(x - 3)$ is 16.

\begin{enumerate}[label=(\roman*)]
\item Find the values of $a$ and $b$. [5]

\item Hence verify that $f(2) = 0$, and factorise $f(x)$ completely. [3]
\end{enumerate}

\hfill \mbox{\textit{OCR C2  Q5 [8]}}