C-4)

f(x)=y dersek

x=(y+1)/(3-y)

x(3-y)=y+1

3x-xy=y+1

3x-1=y+xy

3x-1=y(1+x)

f(x)=3x-1/1+x

f-1(x)=-x-1/x-3

f-1(5/2)=-5/2-1/5/2-3

=-7/2/-1/2

=7