Question

find f[f(x)] and g[f(x)]

f(x)=4x^2-1; g(x)=4/x

Answer 1

f(f(x))

= f(4x^2 - 1)
= 4(x^2 - 1)^2 - 1
don't know if you have to expand that, leave that up to you

g(f(x))
= g(4x^2 - 1)
= 4/(4x^2 - 1)