I dont know why this was wrong ?? anyone know

Answer:
= f(x) = x²+16
is correct.
Step-by-step explanation:
[tex] \dashrightarrow f( \rm x) = (x - 4)(x - 4)[/tex]
[tex] \\ \\ [/tex]
[tex] \dashrightarrow f( \rm x) = \: {x}^{2} - 4x - 4x + 16[/tex]
[tex] \\ \\ [/tex]
[tex] \dashrightarrow f( \rm x) = \: {x}^{2} - 8x + 16[/tex]