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Exercise 1

Avg difficulty 2.5

Consider the matrix and vectors A=[8−105−7],v1=[21],   v2=[11]A = \left[\begin{array}{rr} 8 & -10 \\ 5 & -7 \\ \end{array}\right],\qquad \vvec_1=\twovec{2}{1},~~~ \vvec_2=\twovec{1}{1}.

  1. Show that v1\vvec_1 and v2\vvec_2 are eigenvectors of AA and find their associated eigenvalues.

  2. Express the vector x=[−4−1]\xvec = \twovec{-4}{-1} as a linear combination of v1\vvec_1 and v2\vvec_2.

  3. Use this expression to compute AxA\xvec, A2xA^2\xvec, and A−1xA^{-1}\xvec as a linear combination of eigenvectors.

Austin, Understanding Linear Algebra, §4.1 An introduction to eigenvalues and eigenvectors, Exercise 1

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Adapted from Understanding Linear Algebra © 2023 David Austin. Licensed under CC BY 4.0. Source: Understanding Linear Algebra. Imported at revision 3e6dced.