Question 163840
f(x) = -4x + 3 and g(x) = 1/x + 2  

f(g(x)) = f(1/x + 2)
     = -4*(1/x + 2) + 3
     = -4/x - 8 + 3
     = -4/x - 5
Restriction for f(g(x)) is {{{x <> 0}}}

g(f(x)) = g(-4x + 3)
     = {{{1/(-4x + 3) + 2}}}
     = {{{(1 + 2*(-4x + 3))/(-4x + 3)}}}
     = {{{(1 - 8x + 6)/(-4x + 3)}}}
     = {{{(7 - 8x)/(-4x + 3)}}}
Restriction for g(f(x)) is {{{-4x + 3 <> 0}}}
   so it means {{{x <> 3/4}}}