Calculate $f(3)$ such that $f(f(x))=x^2-5x+9$ How can one calculate $f(3)$ when $f(f(x))=x^2-5x+9$
I tried this:
$f(f(3))=3$
I'm stuck here.

$f(f(f(x))) = f(x^2 - 5x +9) = f(x)^2 - 5 f(x) + 9$.
set $x = 3$, then $f(3) = f(3)^2 - 5 f(3) + 9$. then $f(3) = 3$
