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20.7: End-of-Appendix Materials

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    57815
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    Exercises

    1. Prove \(\mathbf{A} + \mathbf{0} = \mathbf{0} + \mathbf{A} = \mathbf{A}\).
    2. Prove matrix addition is commutative.
    3. Prove matrix addition is associative.
    4. Prove that scalar multiplication is associative.
    5. Prove that scalar multiplication is distributive over addition.
    6. Using a counterexample, prove that matrix multiplication is not commutative when only one of the matrices is diagonal (thus showing that \emph{both} must be diagonal).
    7. Let \(\mathbf{A}\) be any square matrix. Show that \(\frac{(\mathbf{A}+\mathbf{A}^\prime)}{2}\) is symmetric.
    8. Determine the determinant of \(\mathbf{J}_{10}\).
    9. Determine the rank of \(\mathbf{J}_{10}\).
    10. Prove that \(\mathbf{j}_{10}\ \mathbf{j}_{10}^\prime\) is not positive definite.
    11. Prove that \(\mathbf{j}_{10}^\prime\ \mathbf{j}_{10}\) \emph{is} positive definite.
    12. Prove \((\mathbf{AB})^{\prime} = \mathbf{B^{\prime}A^{\prime}}\) from Section 20.5.
    13. Prove \((\mathbf{AB})^{-1} = \mathbf{B^{-1}A^{-1}}\) from Section 20.5.
    14. Prove Lemma 20.5.1.
    15. Prove Lemma 20.5.2.
    16. Prove Lemma 20.5.3.
    17. Prove Lemma 20.6.5.
    18. Prove Lemma 20.6.6.
    19. Prove Lemma 20.6.7.

    This page titled 20.7: End-of-Appendix Materials is shared under a CC BY-NC-SA 4.0 license and was authored, remixed, and/or curated by Ole Forsberg.

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