Answer
(a) Function. Domain $\{2,4,6,8 \}$, range $\{5,6,7,8 \}$.
(b) Not a function.
(c) Not a function.
(d) Function. Domain $(-\infty,\infty)$, range $[2,\infty)$.
Work Step by Step
(a) Function. Domain $\{2,4,6,8 \}$, range $\{5,6,7,8 \}$.
(b) Not a function because for $x=1$ there are two $y$ values $3,7$.
(c) Not a function because the curve will not pass a vertical line test.
(d) Function. Domain $(-\infty,\infty)$, range $[2,\infty)$.
