OCR FP1 2013 June — Question 2 7 marks

Exam BoardOCR
ModuleFP1 (Further Pure Mathematics 1)
Year2013
SessionJune
Marks7
PaperDownload PDF ↗
Mark schemeDownload PDF ↗
TopicMatrices
TypeMatrix arithmetic operations
DifficultyModerate -0.8 This is a straightforward matrix arithmetic question testing basic operations (scalar multiplication, subtraction, and multiplication) with simple numbers. Part (i) is routine calculation, and part (ii) requires recognizing that a 2×2 matrix formed from CB needs determinant checking—standard FP1 content but below average difficulty even for Further Maths due to minimal conceptual demand.
Spec4.03b Matrix operations: addition, multiplication, scalar4.03l Singular/non-singular matrices

2 The matrices \(\mathbf { A } , \mathbf { B }\) and \(\mathbf { C }\) are given by \(\mathbf { A } = \left( \begin{array} { l l } 5 & 1 \end{array} \right) , \mathbf { B } = \left( \begin{array} { l l } 2 & - 5 \end{array} \right)\) and \(\mathbf { C } = \binom { 3 } { 2 }\).
  1. Find \(3 \mathbf { A } - 4 \mathbf { B }\).
  2. Find CB. Determine whether \(\mathbf { C B }\) is singular or non-singular, giving a reason for your answer.

Question 2(i):
AnswerMarks Guidance
AnswerMarks Guidance
\((7 \quad 23)\)B1B1 Each element correct, missing brackets B1 only
[2]
Question 2(ii):
AnswerMarks Guidance
AnswerMarks Guidance
\(\begin{pmatrix} 6 & -15 \\ 4 & -10 \end{pmatrix}\)M1 Obtain \(2 \times 2\) matrix
A1Obtain 2 correct elements
A1Obtain other 2 correct elements
\(\det \mathbf{CB} = 0\)A1FT Obtain their det CB, must be a \(2 \times 2\) matrix
singularA1FT Correct conclusion from their det CB
[5]
## Question 2(i):

| Answer | Marks | Guidance |
|--------|-------|----------|
| $(7 \quad 23)$ | B1B1 | Each element correct, missing brackets B1 only |
| **[2]** | | |

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## Question 2(ii):

| Answer | Marks | Guidance |
|--------|-------|----------|
| $\begin{pmatrix} 6 & -15 \\ 4 & -10 \end{pmatrix}$ | M1 | Obtain $2 \times 2$ matrix |
| | A1 | Obtain 2 correct elements |
| | A1 | Obtain other 2 correct elements |
| $\det \mathbf{CB} = 0$ | A1FT | Obtain their det **CB**, must be a $2 \times 2$ matrix |
| singular | A1FT | Correct conclusion from their det **CB** |
| **[5]** | | |

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2 The matrices $\mathbf { A } , \mathbf { B }$ and $\mathbf { C }$ are given by $\mathbf { A } = \left( \begin{array} { l l } 5 & 1 \end{array} \right) , \mathbf { B } = \left( \begin{array} { l l } 2 & - 5 \end{array} \right)$ and $\mathbf { C } = \binom { 3 } { 2 }$.\\
(i) Find $3 \mathbf { A } - 4 \mathbf { B }$.\\
(ii) Find CB. Determine whether $\mathbf { C B }$ is singular or non-singular, giving a reason for your answer.

\hfill \mbox{\textit{OCR FP1 2013 Q2 [7]}}