We consider a power series $f = \lambda z + F, F \in O_2, \lambda = (f)_1 \neq 0$. Show that there exists a unique series $h \in O_1$ such that $h \circ f = I$, and that $(h)_1 = 1/\lambda$.
We consider a power series $f = \lambda z + F, F \in O_2, \lambda = (f)_1 \neq 0$. Show that there exists a unique series $h \in O_1$ such that $h \circ f = I$, and that $(h)_1 = 1/\lambda$.