\[\sqrt{x}\]
\[x = 0 \Longrightarrow y = 0\]
\[x = 4 \Longrightarrow y = 2\]
\[x = 6 \Longrightarrow y = \sqrt{6} \approx 2,5\]
\[x = 10 \Longrightarrow y = \sqrt{10} \approx 3,2\]