CAIE P2 2006 November — Question 1 4 marks

Exam BoardCAIE
ModuleP2 (Pure Mathematics 2)
Year2006
SessionNovember
Marks4
PaperDownload PDF ↗
Mark schemeDownload PDF ↗
TopicModulus function
TypeSolve |linear| > |linear|
DifficultyStandard +0.3 This is a straightforward modulus inequality requiring consideration of critical points (x = 0 and x = 1/2) and testing regions, which is a standard technique taught in P2. While it requires systematic case analysis, it's a routine application of modulus inequality methods with no novel insight needed, making it slightly easier than average.
Spec1.02l Modulus function: notation, relations, equations and inequalities

1 Solve the inequality \(| 2 x - 1 | > | x |\).

AnswerMarks Guidance
State or imply non-modular inequality \((2x-1)^2 > x^4\) or corresponding quadratic equation or pair of linear equations \(2x - 1 = \pm x\)M1
Make reasonable solution attempt at a 3-term quadratic, or solve two linear equationsM1
Obtain critical values \(x = 1\) and \(x = -\frac{1}{3}\)A1
State answer \(x < -\frac{1}{3}, x > 1\)A1 4 marks
OR: Obtain critical value \(x = 1\) from a graphical method, or by inspection, or by solving a linear inequality or linear equationB1
Obtain the critical value \(x = -\frac{1}{3}\) similarlyB2
State answer \(x < -\frac{1}{3}, x > 1\)B1 4 marks
State or imply non-modular inequality $(2x-1)^2 > x^4$ or corresponding quadratic equation or pair of linear equations $2x - 1 = \pm x$ | M1 |
Make reasonable solution attempt at a 3-term quadratic, or solve two linear equations | M1 |
Obtain critical values $x = 1$ and $x = -\frac{1}{3}$ | A1 |
State answer $x < -\frac{1}{3}, x > 1$ | A1 | 4 marks |

OR: Obtain critical value $x = 1$ from a graphical method, or by inspection, or by solving a linear inequality or linear equation | B1 |
Obtain the critical value $x = -\frac{1}{3}$ similarly | B2 |
State answer $x < -\frac{1}{3}, x > 1$ | B1 | 4 marks |
1 Solve the inequality $| 2 x - 1 | > | x |$.

\hfill \mbox{\textit{CAIE P2 2006 Q1 [4]}}