한걸음

뒤늦게 정리하는 Problem set 1.4 : 1 ~ 3 종이에 스캔하지 말고 이번엔 수식을 직접 적어서 포스팅한다. Test for exactness, If not, use an integrating factors. Problem 1. Find Solution : $ 2xy dx + x^2 dy = 0 $ Assume that : $$ M = 2xy , N = x^2 $$ By the assumption of continuity the two second partial derivatives are equals. $$ \frac {\partial M}{\partial y} = 2 x $$ $$ \frac {\partial N}{\partial x} = 2 x $$ Because of M = N, The..