Question

Suppose f(x) and g(t) are given by:
f(x) = 3x, x>= 0
f(x) = x^2 x < 0

g(t) = 5t, t<0
g(t) = t^2, t>= 0

Show that (g o f)(x) is given by:
(g o f)(x) = 9x^2, x>=0
(g o f)(x) = x^4, x<0