The given function is
[tex]f(x)=x^2+3[/tex]Its inverse can be founded by this way
[tex]\begin{gathered} y=x^2+3 \\ x=y^2+3 \\ x-3=y^2 \\ y^2=x-3 \\ y=-\sqrt[]{x-3} \\ f^{-1}(x)=-\sqrt[]{x-3} \end{gathered}[/tex]Now we need to graph them with the line of symmetry y = x