Since \( f(x) \) is a rational function of degree \( \max(\deg extnum, \deg extden) = 3 \), then \( f(f(x)) \) has degree at most \( 3 imes 3 = 9 \). So \( f(f(x)) - x = 0 \) is a rational equation whose numerator is a polynomial of degree at most 9. - Appfinity Technologies