# Linear algebra

1. Let a1, a2, a3 be linearly independent vectors in R3, and let A = [a1 a2 a3]. Which of the following statements are true?

a) The reduced row echelon form of A is I3

b) The rank of A is 3

c) The system [A|b] has a unique solution for any vector b in R3

d) (a), (b) and (c) are all true

e) (a) and (b) are both true, but not (c)

2. Show that span (u,v) = span (u, u+v) for any vectors u and v.

3. If A is a diagonalisable matrix and all of its eigenvalues satisfy |λ| < 1, prove that An approaches the zero matrix as n gets large.

4. Prove that given any n real numbers λ1, ..., λn, there exists a symmetric n x n matrix with λ1, ..., λn as its eigenvalues.

5. Find the LU factorisation of the matrix shown below:

A =

6. Write the given permutation matrix shown below; as a product of elementary (row interchange) matrices.

B = ?

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#### Solution Summary

The solution provides a series of linear algebra problems that involve span and LU factoring