To get the inverse of the function given by y=2x-4, we proceed as follows;
make x the subject;
y=2x-4
y+4=2x
thus;
x=1/2(y+4)
next, we replace y by x and x by y^-1 to get our inverse, therefore we shall have the inverse as:
y^-1=1/2(x+4)
this can be written as:
f^-1(x)=1/2(x+4)