MathDB
Putnam 1951 B1

Source:

May 25, 2022
Putnam

Problem Statement

Find the conditions that the functions M(x,y)M(x, y) and N(x,y)N (x, y) must satisfy in order that the differential equation Mdx+Ndy=0Mdx + Ndy =0 shall have an integrating factor of the form f(xy).f(xy). You may assume that MM and NN have continuous partial derivatives of all orders.