OCR H240/03 2018 June — Question 2 3 marks

Exam BoardOCR
ModuleH240/03 (Pure Mathematics and Mechanics)
Year2018
SessionJune
Marks3
PaperDownload PDF ↗
TopicModulus function
TypeSolve |linear| = |linear| (both linear inside)
DifficultyModerate -0.8 This is a straightforward modulus equation requiring consideration of cases based on critical values x = 0.5 and x = -3. Students need to square both sides or systematically check regions, but the algebra is simple and the method is standard textbook material with no conceptual surprises.
Spec1.02l Modulus function: notation, relations, equations and inequalities1.02t Solve modulus equations: graphically with modulus function

2 Solve the equation \(| 2 x - 1 | = | x + 3 |\).

Question 2:
AnswerMarks Guidance
Attempt process for finding both valuesM1 1.1a e.g. squaring both sides to obtain 3 terms on both sides: \((4x^2 - 4x + 1 = x^2 + 6x + 9)\); or consider two linear equations \((2x-1) = \pm(x+3)\)
\(3x^2 - 10x - 8 (= 0)\)A1 1.1 1 correct solution for A1
Obtain \(4\) and \(-\dfrac{2}{3}\)A1 1.1 [3] BC; SC one correct solution from one linear equation B1
## Question 2:

Attempt process for finding both values | M1 1.1a | e.g. squaring both sides to obtain 3 terms on both sides: $(4x^2 - 4x + 1 = x^2 + 6x + 9)$; or consider two linear equations $(2x-1) = \pm(x+3)$

$3x^2 - 10x - 8 (= 0)$ | A1 1.1 | 1 correct solution for A1

Obtain $4$ and $-\dfrac{2}{3}$ | A1 1.1 [3] | **BC**; **SC** one correct solution from one linear equation B1

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2 Solve the equation $| 2 x - 1 | = | x + 3 |$.

\hfill \mbox{\textit{OCR H240/03 2018 Q2 [3]}}