I have a big problem to solve this system $\Delta f-hf^2=0$ $|\nabla f|^2+hf^3=0$ where $h$ is a constant, $f$ is a 2-dimensional smooth function, $\Delta f$ is Laplacian of $f$ (i.e. $\Delta f=f_{xx}+f_{yy}$) and $\nabla f$ is the gradient of $f$. is there a solution? Thank you for help