CompleteIntegral
CompleteIntegral[pde, u, {x1, ..., xn}] gives a complete integral u for the first-order partial differential equation pde, with independent variables {x1, ..., xn}.
Examples
Find complete integral of a PDE:
CompleteIntegral[D[u[x, y], x] + D[u[x, y], y] == 1, u[x, y], {x, y}]Please visit the official Wolfram Language Reference for more details.