Let f(x):=1/x^2, x not equal 0, x belongs R
a) Determine the direct image f(E) where E:= (x belongs R : 1<=x<=2)
b) Determine the inverse image f^(-1)(G) where G:= (x belongs R : 1<=x<=4)

My Solution:

A) Let f: R -> R be defined by f(x):=1/x^2. Then, the direct image of the set E:=(x:1<=x<=2) is the set f(E)=(y:1<=x<=1/4).
If G:= (y : 1<=x<=4), then the inverse image of G is the set f^-1 (G)=(x:

And here I don't quite understand how to find an inverse image. Please help.