Question

are f(x)=2x-4 and g(x)=1/2x+2 inverse of each other?

Answer 1

to find the inverse of y = 2x - 4

swap x and y

x = 2y - 4

now make y the subject

Answer 2

yes

Answer 3

y=2x-4
y+4=2x
x=(y+4)/2
interchange x and y:
y=(x+4)/2