. The parametric form of the straight line in R³ corresponding to the null-space of A=\left(\begin{array}{ccc}

1 & 2 & 3 \\

0 & 1 & -2 \\

0 & -1 & 2

\end{array}\right) \text { is given by }\left(\begin{array}{l}

x \\

y \\

z

\end{array}\right)=