a) f(4) = 9
b) f(-5) = -9
c) f(0) = 1
d) f(1/2) = 2
Explanation:[tex]\begin{gathered} \text{function:} \\ \text{f(x) = 2x + 1} \end{gathered}[/tex][tex]\begin{gathered} a)\text{ f(4): x = 4} \\ f(4)=\text{ 2(4) + 1} \\ f(4)\text{ = 9} \end{gathered}[/tex][tex]\begin{gathered} b)\text{ f(-5): x = -5} \\ f(-5)\text{ = 2(-5) + 1} \\ f(-5)\text{ = -10 + 1} \\ f(-5)\text{ = -9} \end{gathered}[/tex][tex]\begin{gathered} c)\text{ }f(0)\colon\text{ x = 0} \\ f(0)\text{ = 2(0) + 1} \\ f(0)\text{ = 0 + 1} \\ f(0)\text{ = 1} \end{gathered}[/tex][tex]\begin{gathered} d)\text{ }f(\frac{1}{2})\colon\text{ x = 1/2} \\ f(\frac{1}{2})\text{ = 2(}\frac{\text{1}}{2})\text{ + 1} \\ f(\frac{1}{2})\text{ =}1\text{ + 1} \\ f(\frac{1}{2})\text{ = 2} \end{gathered}[/tex]