AQA FP1 2011 June — Question 7 9 marks

Exam BoardAQA
ModuleFP1 (Further Pure Mathematics 1)
Year2011
SessionJune
Marks9
PaperDownload PDF ↗
Mark schemeDownload PDF ↗
TopicLinear transformations
TypeMatrix powers and repeated transformations
DifficultyModerate -0.3 This is a standard FP1 matrix transformation question requiring matrix multiplication and recognition of rotation matrices. Part (a) involves routine calculation, while part (b) requires identifying that A represents a rotation by 120° (or reflection composition), which is a well-practiced skill at this level. The presence of √3 is a clear hint toward 60°/120° angles, making this slightly easier than average.
Spec4.03b Matrix operations: addition, multiplication, scalar4.03d Linear transformations 2D: reflection, rotation, enlargement, shear4.03e Successive transformations: matrix products

7 The matrix \(\mathbf { A }\) is defined by $$\mathbf { A } = \left[ \begin{array} { c c } - 1 & - \sqrt { 3 } \\ \sqrt { 3 } & - 1 \end{array} \right]$$
    1. Calculate the matrix \(\mathbf { A } ^ { 2 }\).
    2. Show that \(\mathbf { A } ^ { 3 } = k \mathbf { I }\), where \(k\) is an integer and \(\mathbf { I }\) is the \(2 \times 2\) identity matrix.
  1. Describe the single geometrical transformation, or combination of two geometrical transformations, corresponding to each of the matrices:
    1. \(\mathrm { A } ^ { 3 }\);
    2. A.

Question 7:
Part (a)(i):
AnswerMarks Guidance
Answer/WorkingMarks Guidance
\(\mathbf{A}^2 = \begin{pmatrix} -2 & 2\sqrt{3} \\ -2\sqrt{3} & -2 \end{pmatrix}\)M1A1 M1 if at least two entries correct
Total2
Part (a)(ii):
AnswerMarks Guidance
Answer/WorkingMarks Guidance
\(\mathbf{A}^3 = \begin{pmatrix} 8 & 0 \\ 0 & 8 \end{pmatrix}\)M1 if at least two entries correct
\(\ldots = 8\mathbf{I}\)A1
Total2
Part (b)(i):
AnswerMarks Guidance
Answer/WorkingMarks Guidance
\(A^3\) gives enlargement with SF 8 (centre the origin)M1A1F M1 for enlargement (only); ft wrong value for \(k\)
Total2
Part (b)(ii):
AnswerMarks Guidance
Answer/WorkingMarks Guidance
Enlargement and rotationM1 Some detail needed
Enlargement scale factor 2A1
Rotation through \(120°\) (antic'wise)A1
Total3
## Question 7:

### Part (a)(i):
| Answer/Working | Marks | Guidance |
|---|---|---|
| $\mathbf{A}^2 = \begin{pmatrix} -2 & 2\sqrt{3} \\ -2\sqrt{3} & -2 \end{pmatrix}$ | M1A1 | M1 if at least two entries correct |
| **Total** | **2** | |

### Part (a)(ii):
| Answer/Working | Marks | Guidance |
|---|---|---|
| $\mathbf{A}^3 = \begin{pmatrix} 8 & 0 \\ 0 & 8 \end{pmatrix}$ | M1 | if at least two entries correct |
| $\ldots = 8\mathbf{I}$ | A1 | |
| **Total** | **2** | |

### Part (b)(i):
| Answer/Working | Marks | Guidance |
|---|---|---|
| $A^3$ gives enlargement with SF 8 (centre the origin) | M1A1F | M1 for enlargement (only); ft wrong value for $k$ |
| **Total** | **2** | |

### Part (b)(ii):
| Answer/Working | Marks | Guidance |
|---|---|---|
| Enlargement and rotation | M1 | Some detail needed |
| Enlargement scale factor 2 | A1 | |
| Rotation through $120°$ (antic'wise) | A1 | |
| **Total** | **3** | |

---
7 The matrix $\mathbf { A }$ is defined by

$$\mathbf { A } = \left[ \begin{array} { c c } 
- 1 & - \sqrt { 3 } \\
\sqrt { 3 } & - 1
\end{array} \right]$$
\begin{enumerate}[label=(\alph*)]
\item \begin{enumerate}[label=(\roman*)]
\item Calculate the matrix $\mathbf { A } ^ { 2 }$.
\item Show that $\mathbf { A } ^ { 3 } = k \mathbf { I }$, where $k$ is an integer and $\mathbf { I }$ is the $2 \times 2$ identity matrix.
\end{enumerate}\item Describe the single geometrical transformation, or combination of two geometrical transformations, corresponding to each of the matrices:
\begin{enumerate}[label=(\roman*)]
\item $\mathrm { A } ^ { 3 }$;
\item A.
\end{enumerate}\end{enumerate}

\hfill \mbox{\textit{AQA FP1 2011 Q7 [9]}}