Consider matrix A $=$

$$

$$

$131$

$251$

$282$

$$

$$ and vector b $=$

$$

$$

$2$

$1$

$3$

$$

$.$

$($a$)$ Show that b is a linear combination of the column vectors a$1,$ a$2$ and a$3$ of A$.$

$($b$)$ List three other vectors in Span $\{$a$1,$ a$2,$ a$3\}.$