Question 13782
f(x)=3x^2-5              g(x)= 8/x

fog(x)=f(g(x))=f(8/x)={{{3(8/x)^2-5}}}={{{3(64/x^2)-5}}}={{{192/x^2-5}}}

gof(x)=g(f(x))=g{{{(3x^2-5)}}}={{{8/(3x^2-5)}}}

OK