where \(a\) and \(b\) are constants and \(a \neq 1\).

What happens if \(a=1\)?

Solve for \(x\), \(y\) and \(z\) the equations:
\[\begin{align*}
2x-y+z&{}=0,\\
3y+z&{}=0,\\
x+y+az&{}=b,
\end{align*}\]

where \(a\) and \(b\) are constants and \(a \neq 1\).

What happens if \(a=1\)?