kittycat5556 kittycat5556 27-11-2022 Mathematics contestada Classify the following second-order partial differential equations. [tex]1.1 \quad 3 \frac{\partial^2 \phi}{\partial x^2}+\frac{\partial^2 \phi}{\partial x \partial y}+2 \frac{\partial^2 \phi}{\partial y^2}=0[/tex]
