Solving functional nonlinear equation

[Dorian]

Hi  all,

How do I solve  the following functional nonlinear equation using octave

f(x,y)= (-1/a^2)*(x*y)^(1/a-1)+(1/a)*x^(1/a-1)+(1/a)*y^(1/a-1) =0

where  "a"  is positive parameter.  

If there is a way to plot  f(x,y) for different values of "a" 
it will be very appreciated.

Thanking you in advance

Dorian