CAIE P1 2016 November — Question 1 4 marks

Exam BoardCAIE
ModuleP1 (Pure Mathematics 1)
Year2016
SessionNovember
Marks4
PaperDownload PDF ↗
Mark schemeDownload PDF ↗
TopicInequalities
TypeComplete the square technique
DifficultyModerate -0.8 This is a straightforward two-part question testing basic completing the square (routine algebraic manipulation) followed by solving a simple quadratic inequality. Both parts are standard textbook exercises requiring only direct application of well-practiced techniques with no problem-solving insight needed.
Spec1.02e Complete the square: quadratic polynomials and turning points1.02g Inequalities: linear and quadratic in single variable

1
  1. Express \(x ^ { 2 } + 6 x + 2\) in the form \(( x + a ) ^ { 2 } + b\), where \(a\) and \(b\) are constants.
  2. Hence, or otherwise, find the set of values of \(x\) for which \(x ^ { 2 } + 6 x + 2 > 9\).

Question 1:
Part (i):
AnswerMarks Guidance
\((x+3)^2 - 7\)B1B1 [2] For \(a = 3\), \(b = -7\)
Part (ii):
AnswerMarks Guidance
\(1, -7\) seenB1 \(x > 1\) or \(x < -7\); Allow \(x \leqslant -7, x \geqslant 1\) oe
\(x > 1\), \(x < -7\) oeB1 [2]
## Question 1:

### Part (i):
$(x+3)^2 - 7$ | **B1B1** [2] | For $a = 3$, $b = -7$

### Part (ii):
$1, -7$ seen | **B1** | $x > 1$ or $x < -7$; Allow $x \leqslant -7, x \geqslant 1$ oe
$x > 1$, $x < -7$ oe | **B1** [2] |

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1 (i) Express $x ^ { 2 } + 6 x + 2$ in the form $( x + a ) ^ { 2 } + b$, where $a$ and $b$ are constants.\\
(ii) Hence, or otherwise, find the set of values of $x$ for which $x ^ { 2 } + 6 x + 2 > 9$.

\hfill \mbox{\textit{CAIE P1 2016 Q1 [4]}}