On the general solution of the d'Alembert equation with nonlinear eikonal constraint

via solutions of the system of PDE (1). 2. Integration of the system (1): The list of principal results. Below we adduce assertions giving general solutions of the system of PDE (1) with arbitrary n ∈ N provided u(x) ∈ C(R,R), and with n = 4, 5, provided u(x) ∈ C(C,C). Theorem 1. Let u(x) be sufficiently smooth real function on n real variables x0, . . . , xn−1. Then the general solution of the system of nonlinear PDE (1) is given by the following formula: