| Exam Board | CAIE |
| Module | FP1 (Further Pure Mathematics 1) |
| Year | 2011 |
| Session | November |
| Topic | Invariant lines and eigenvalues and vectors |
8 The vector \(\mathbf { e }\) is an eigenvector of the matrix \(\mathbf { A }\), with corresponding eigenvalue \(\lambda\), and is also an eigenvector of the matrix \(\mathbf { B }\), with corresponding eigenvalue \(\mu\). Show that \(\mathbf { e }\) is an eigenvector of the matrix \(\mathbf { A B }\) with corresponding eigenvalue \(\lambda \mu\).
State the eigenvalues of the matrix \(\mathbf { C }\), where
$$\mathbf { C } = \left( \begin{array} { r r r }
- 1 & - 1 & 3
0 & 1 & 2
0 & 0 & 2
\end{array} \right) ,$$
and find corresponding eigenvectors.
Show that \(\left( \begin{array} { l } 1
6
3 \end{array} \right)\) is an eigenvector of the matrix \(\mathbf { D }\), where
$$\mathbf { D } = \left( \begin{array} { r r r }
1 & - 1 & 1
- 6 & - 3 & 4
- 9 & - 3 & 7
\end{array} \right) ,$$
and state the corresponding eigenvalue.
Hence state an eigenvector of the matrix CD and give the corresponding eigenvalue.