It is just a very simple substitution operation...
let x= 2
so the function f(x) would be:
[tex]f(2) =4(2)^2-2(2)+1=4(4)-4+1=16-4+1=13[/tex]
That is for the first one
and so on for the other two
can you follow this and do the other two??
[tex]f(5)=4(5)^2-4(5)+1=4*25-20+1=81[/tex]
[tex]f(4)=4(4)^2-4(4)+1=4*16-16+1=49[/tex]
f(5)-f(4)=81-49=32