Quiz 4

1. Write clear sentences explaining how you can tell:
   1. Whether it is possible to multiply two matrices together.
   2. What the size of the resulting matrix will be.
2. Solve the following system of equations (find the intersection of the two lines):

$$ \begin{eqnarray} 2x + 3y & = & 7 \\ -2x - 5y & = & 11 \end{eqnarray} $$

3. Using the matrices A and B below, compute:
   1. A + B
   2. A - 2*B
   3. A*B

$$ A = \begin{bmatrix} 2 & 3 & 1 \\ -1 & 5 & 0 \\ 0 & -2 & -2 \end{bmatrix} $$ $$ B = \begin{bmatrix} 1 & 1 & 2 \\ 3 & -2 & 1 \\ -5 & 0 & -1 \end{bmatrix} $$