assignment question



Hello:

Why doesn't the second assignment work? I want g(x):=x; how do I do that?

(%i1)    f(x):=x^2;
(%o1)   f(x):=x^2
(%i2)    g(x):=diff(f(x),x);
(%o2)   g(x):=diff(f(x),x)

Thanks,
Robert