> N[8]:=(xi,eta) -> 9*(1+3*xi)*(1-xi^2)*(1+eta)*eta/32;

                                                 2
     N[8] := (xi, eta) -> 9/32 (1 + 3 xi) (1 - xi ) (1 + eta) eta

> plot3d(N[8],-1..1,-1..1,grid=[15,15],axes=boxed,scaling=constrained,
> style=patch,orientation=[-60,60]);

> 
> 
