There is problem to find Lagrange's solution of first order partial differential equation:

$\displaystyle z=xp+yq+a\sqrt{x^2+y^2+z^2}$

Where

$\displaystyle p=\frac{\partial z}{\partial x}$ and $\displaystyle q=\frac{\partial z}{\partial y}$, and $\displaystyle z$ is a dependent variable.

Thanks in advance..