\[\sqrt{a(x - 2)} = 0\]
\[a(x - 2) = 0\]
\[x - 2 = 0\ \ \]
\[x = 2.\]
\[a = 0 \Longrightarrow x - любое.\]
\[a \neq 0 \Longrightarrow x = 2.\]