I have to find the particular integral of this partial differential eqn.
Help me in the next steps....
Is "D" just the unknown function? If so what do D' and D'' mean? The derivative, I presume, but with respect to what variable? If only with respect to one of x and y, this is not a partial differential equation, just an ordinary differential equation with an additional parameter. You seem to be trying to do the problem as if it were a linear equation with constant coefficient but if D is the unknown function, this is NOT a linear equation. Please explain.