CAIE P2 2013 June — Question 3 4 marks

Exam BoardCAIE
ModuleP2 (Pure Mathematics 2)
Year2013
SessionJune
Marks4
PaperDownload PDF ↗
Mark schemeDownload PDF ↗
TopicFactor & Remainder Theorem
TypeSingle unknown constant
DifficultyModerate -0.8 This is a straightforward application of the factor theorem requiring substitution of x=-1 to find a constant, followed by a simple remainder theorem calculation. Both parts are routine textbook exercises with no problem-solving insight needed, making it easier than average but not trivial since it requires correct algebraic manipulation.
Spec1.02j Manipulate polynomials: expanding, factorising, division, factor theorem

3
  1. The polynomial \(2 x ^ { 3 } + a x ^ { 2 } - a x - 12\), where \(a\) is a constant, is denoted by \(\mathrm { p } ( x )\). It is given that \(( x + 1 )\) is a factor of \(\mathrm { p } ( x )\). Find the value of \(a\).
  2. When \(a\) has this value, find the remainder when \(\mathrm { p } ( x )\) is divided by \(( x + 3 )\).

AnswerMarks Guidance
(i) Substitute \(x = -1\) and equate to zeroM1
Obtain answer \(a = 7\)A1 [2]
(ii) Substitute \(x = -3\) and evaluate expressionM1
Obtain answer 18A1 [2]
**(i)** Substitute $x = -1$ and equate to zero | M1 |
Obtain answer $a = 7$ | A1 | [2]

**(ii)** Substitute $x = -3$ and evaluate expression | M1 |
Obtain answer 18 | A1 | [2]
3 (i) The polynomial $2 x ^ { 3 } + a x ^ { 2 } - a x - 12$, where $a$ is a constant, is denoted by $\mathrm { p } ( x )$. It is given that $( x + 1 )$ is a factor of $\mathrm { p } ( x )$. Find the value of $a$.\\
(ii) When $a$ has this value, find the remainder when $\mathrm { p } ( x )$ is divided by $( x + 3 )$.

\hfill \mbox{\textit{CAIE P2 2013 Q3 [4]}}