Solution
= Solution
For a type-two generating function, compare
$$
dF_2=p\,dq+Q\,dP
$$
with
$$
dF_2=\frac{\partial F_2}{\partial q},dq
+\frac{\partial F_2}{\partial P},dP.
$$
The coefficients give the canonical-transformation equations
$$
\boxed{p=\frac{\partial F_2}{\partial q},
\qquad Q=\frac{\partial F_2}{\partial P}}.
$$