Ответ:
\[y = x^{6} - четная.\]

\[- 64 = ( - 2)^{6};\ \ \ \]
\[- 64 \neq 64 \Longrightarrow A \notin y.\]
\[729 = ( - 3)^{6};\ \ \ \ \]
\[729 = 729 \Longrightarrow B \in y.\]
\[64 = 2^{6};\ \ \ \ \ \]
\[64 = 64 \Longrightarrow C \in y.\]
\[y = x^{6} - четная.\]

\[- 64 = ( - 2)^{6};\ \ \ \]
\[- 64 \neq 64 \Longrightarrow A \notin y.\]
\[729 = ( - 3)^{6};\ \ \ \ \]
\[729 = 729 \Longrightarrow B \in y.\]
\[64 = 2^{6};\ \ \ \ \ \]
\[64 = 64 \Longrightarrow C \in y.\]