If you are just supposed to evaluate the a) f(0) and b) f(4) then you would just plug it in the equation.
f(0)=0^2 - 8*0 + 16
f(0)=0 - 0 + 16
f(0)=16
f(4)=4^2 - 8*4 +16
f(4)=16 - 32 + 16
f(4)=0
Feel free to comment any questions and if there is any additional context to the question please say so I can help with that.
