OCR C2 — Question 2 6 marks

Exam BoardOCR
ModuleC2 (Core Mathematics 2)
Marks6
PaperDownload PDF ↗
Mark schemeDownload PDF ↗
TopicFactor & Remainder Theorem
TypeOne unknown constant: find it then solve
DifficultyModerate -0.3 This is a straightforward application of the factor theorem and polynomial division. Part (i) requires substituting x = -1 and solving for k (routine). Part (ii) involves factoring and solving a quadratic after division. Standard C2 content with clear method, slightly easier than average due to the given factor making it mechanical rather than requiring insight.
Spec1.02j Manipulate polynomials: expanding, factorising, division, factor theorem

$$f(x) = x^3 + kx - 20.$$ Given that f(x) is exactly divisible by \((x + 1)\),
  1. find the value of the constant \(k\), [2]
  2. solve the equation \(f(x) = 0\). [4]

$$f(x) = x^3 + kx - 20.$$

Given that f(x) is exactly divisible by $(x + 1)$,

\begin{enumerate}[label=(\roman*)]
\item find the value of the constant $k$, [2]
\item solve the equation $f(x) = 0$. [4]
\end{enumerate}

\hfill \mbox{\textit{OCR C2  Q2 [6]}}