Pre-U Pre-U 9794/1 2014 June — Question 3 3 marks

Exam BoardPre-U
ModulePre-U 9794/1 (Pre-U Mathematics Paper 1)
Year2014
SessionJune
Marks3
TopicInequalities
TypeSolve absolute value inequality
DifficultyEasy -1.2 This is a straightforward absolute value inequality requiring only the standard technique of splitting into two cases: 2x-1 < 3 and 2x-1 > -3, then solving both linear inequalities. It's a routine procedural question with no conceptual challenges, making it easier than average for A-level.
Spec1.02l Modulus function: notation, relations, equations and inequalities

3 Solve the inequality \(| 2 x - 1 | < 3\).

METHOD 1
\(x < 2\) seen — B1
\(2x - 1 < 3\) AND \(-(2x-1) < 3\) seen — M1
Obtain \(-1 < x < 2\) — A1 [3]
METHOD 2
\((2x-1)^2 < 3^2\) seen — B1
Expand and obtain a 3 term quadratic \((x^2 - x - 2 < 0)\) — M1
Obtain \(-1 < x < 2\) — A1
**METHOD 1**
$x < 2$ seen — B1
$2x - 1 < 3$ AND $-(2x-1) < 3$ seen — M1
Obtain $-1 < x < 2$ — A1 **[3]**

**METHOD 2**
$(2x-1)^2 < 3^2$ seen — B1
Expand and obtain a 3 term quadratic $(x^2 - x - 2 < 0)$ — M1
Obtain $-1 < x < 2$ — A1
3 Solve the inequality $| 2 x - 1 | < 3$.

\hfill \mbox{\textit{Pre-U Pre-U 9794/1 2014 Q3 [3]}}