State the order of the pde: $u_x(1+u_x^2)^{-1/2}+u_y(1+u_y^2)^{-1/2}=0$

Question

State the order of the pde: $u_x(1+u_x^2)^{-1/2}+u_y(1+u_y^2)^{-1/2}=0$

Do the $u_x$ and $u_y$ inside the bracket count?

Answer 1

Order 1. Because you have no derivatives of order two or higher. The squares and roots only reflect non-linearity of the PDE.