Question: Newton’s Method, Diff, diff

Hello Guys

I got the Mapple 2022 Student version and I try a couple of time to firgure out why that doesn't work at my Student Version. Please, could anybody help me. Thx a lot. 

Newton Method:

f(x) = x^2 assigned to function why I doesn't have right click for this function?

g(x) = x - f(x)/f'(x);

g(1.3) doesn't work because faild he want 2 arguments. That I figure out if I assigned like this

g(x) := x->x f(x)/f'(x) but he do not calc that right. It make me really creapy. Maybe tha Student version doesn't have this fearure is it possible?

This is another think.

a := x^2;

D(a);
                            2 D(x) x ???? why no 2x?

Next example:

f := x -> 5*x^3 + x - 7

D2f := x -> diff(f(x), x)

                         D2f:=x->d/dx f(x) ??? why not 15x^2+1?