fog

$$\begin{gathered} f\left(x\right)=x^{2 Df:R} \\ g\left(x\right)=\sqrt{x} Dg: x\ge 0 \\ f\left(g\right(x)= x \\ Dfog=[x\in Dg| g(x)\in Df ]=[ x\ge 0 | \sqrt{x } \in R]=[x\ge 0\left] \\ g\right(f\left(x\right))=x \\ Dgof=[x\in Df | f(x)\in Dg]= [x:R| x^2\in x\ge 0] men jag vet inte Dgof? \end{gathered}$$