1. Is the set of matrices below linearly independent or linearly dependent in the vector space $M_{22}$? Why or why not? \begin{equation*} \set{ \begin{bmatrix} 1&3\\-2&4 \end{bmatrix},\, \begin{bmatrix} -2&3\\3&-5 \end{bmatrix},\, \begin{bmatrix} 0&9\\-1&3 \end{bmatrix} } \end{equation*}
  2. Explain the difference between the following two uses of the term “span”:
    1. $S$ is a subset of the vector space $V$ and the span of $S$ is a subspace of $V$.
    2. $W$ is a subspace of the vector space $Y$ and $T$ spans $W$.
  3. The set \begin{equation*} S=\set{ \colvector{6\\2\\1},\, \colvector{4\\-3\\1},\, \colvector{5\\8\\2} } \end{equation*} is linearly independent and spans $\complex{3}$. Write the vector $\vect{x}=\colvector{-6\\2\\2}$ as a linear combination of the elements of $S$. How many ways are there to answer this question, and which theorem allows you to say so?