※ 引述《xoo1208 (RaInBoW)》之銘言：
: Ex： 4xy+6y^2+(2x^2+6xy)y'= 0
(2x + 3y)ydx + (x + 3y)xdy = 0
(x + 3y)d(xy) + xydx = 0
u = xy
(x + 3u/x)du + udx = 0
(x^2 + 3u)du + uxdx = 0
(3/2)d(u^2) + (x^2)du + uxdx = 0
μ = μ(x)
μ'x^2 + 2xμ = xμ
=> μ' = μ/x
=> μ = 1/x
=> (3)d(u^2) + (2x)d(ux) = 0
U = u^2, V = ux
=> 3√U dU + 2VdV = 0
=> 2u^3 + x^2(xy)^2 = C
=> 2x^3 y^3 + x^4 y^2 = C