Please help about functions?

Question

Find 2 functions f(x) and g(x) such that
f(x) ≠ g(x)
and
f[g(x)] = g[f(x)]


^_^
...easy...
^_^

Answer 1

f(x) =x +2
g(x) = x +3

f(x) != g(x)

f(g(x)) = g(f(x)) = x + 5

Answer 2

f: x-> -x
g:x->x

well and for x = 0 both are undefined.

Answer 3

f(x) = x
g(x) = x^2

f(g(x)) = f(x^2) = x^2
g(f(x)) = g(x) = x^2

Answer 4

example
f(x)= x
g(x)= x²
f(x) is different g(x) but
f[g(x)]= g[f(x)],
see:
(x²)=(x)²