\[y = x + 1\]
\[y = 3:\]
\[x + 1 = 3 \Longrightarrow \ \ x = 2.\]
\[y = - 1:\]
\[x + 1 = - 1 \Longrightarrow \ \ x = - 2.\]
\[y = 0:\]
\[x + 1 = 0 \Longrightarrow \ \ x = - 1.\]
\[y = - 2:\]
\[x + 1 = - 2 \Longrightarrow \ \ x = - 3.\ \]