Chapter 4.5, Problem 16P

For Problem 16-18, determine whether the given set of vectors is linearly independent in $M_2\left(ℝ\right)$.

$A_1=\left[\begin{array}{cc}1& 1\\ 0& 1\end{array}\right]$, $A_2=\left[\begin{array}{cc}2& 1\\ 0& -1\end{array}\right]$, $A_3=\left[\begin{array}{cc}3& 6\\ 0& 4\end{array}\right]$