If f:R→R, g :R→R be two functions given by f(x)=2x-3, g(x)=x3+5. Then,fog-1(x) is equal to

f:R→R g:R→R f(x)=2x-3 g(x)=x3+5 ⇒        (fog)(x)=f(g(x))=f(x3+5)=2(x3+5)-3                            =2x3+7Now,     let let     y=2x3+7         2x3=y-7           x=y-721/3       Replacing  x by y, we get               y=x-721/3 ∴        (fog)-1(x)=x-721/3