CAIE P2 2017 March — Question 3 6 marks

Exam BoardCAIE
ModuleP2 (Pure Mathematics 2)
Year2017
SessionMarch
Marks6
PaperDownload PDF ↗
Mark schemeDownload PDF ↗
TopicModulus function
TypeSolve |linear| < |linear|
DifficultyStandard +0.3 Part (i) is a standard modulus inequality requiring squaring both sides or considering cases, yielding a straightforward quadratic inequality. Part (ii) adds a simple substitution step (u = ln y) then exponentiating to find y, but remains routine application of technique with no novel insight required.
Spec1.02g Inequalities: linear and quadratic in single variable1.02l Modulus function: notation, relations, equations and inequalities1.06d Natural logarithm: ln(x) function and properties

3
  1. Solve the inequality \(| 2 x - 5 | < | x + 3 |\).
  2. Hence find the largest integer \(y\) satisfying the inequality \(| 2 \ln y - 5 | < | \ln y + 3 |\).

Question 3(i):
AnswerMarks Guidance
AnswerMark Guidance
State or imply non-modulus inequality \((2x-5)^2 < (x+3)^2\) or corresponding equation or pair of linear equationsB1
Attempt solution of 3-term quadratic inequality or equation or of 2 linear equationsM1
Obtain critical values \(\frac{2}{3}\) and \(8\)A1
State answer \(\frac{2}{3} < x < 8\)A1
Question 3(ii):
AnswerMarks Guidance
AnswerMark Guidance
Attempt to find \(y\) from \(\ln y =\) upper limit of answer to part (i)M1
Obtain \(2980\)A1
## Question 3(i):

| Answer | Mark | Guidance |
|--------|------|----------|
| State or imply non-modulus inequality $(2x-5)^2 < (x+3)^2$ or corresponding equation or pair of linear equations | B1 | |
| Attempt solution of 3-term quadratic inequality or equation or of 2 linear equations | M1 | |
| Obtain critical values $\frac{2}{3}$ and $8$ | A1 | |
| State answer $\frac{2}{3} < x < 8$ | A1 | |

## Question 3(ii):

| Answer | Mark | Guidance |
|--------|------|----------|
| Attempt to find $y$ from $\ln y =$ upper limit of answer to part (i) | M1 | |
| Obtain $2980$ | A1 | |

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3 (i) Solve the inequality $| 2 x - 5 | < | x + 3 |$.\\

(ii) Hence find the largest integer $y$ satisfying the inequality $| 2 \ln y - 5 | < | \ln y + 3 |$.\\

\hfill \mbox{\textit{CAIE P2 2017 Q3 [6]}}