We need to evaluate the given function at these x values:
f(x) = 6x + 12
Just plug in the x-values into x of the functional expression. Simple!
a)
x = 4
f(4) = 6(4) + 12 = 24 + 12 = 36
b)
x = -13
f(-13) = 6(-13) + 12 = -78 + 12 = -66
c)
x = 12/31
[tex]f(\frac{12}{31})=6(\frac{12}{31})+12=\frac{72}{31}+12=\frac{444}{31}[/tex]