Start from the 'outermost' part of f(x); in other words, the square root. Set
[tex]p(x)=\sqrt{x}[/tex]
Then, the next 'layer' is the +3, define q(x) as shown below
[tex]q(x)=x+3[/tex]
Finally, set
[tex]r(x)=x^2[/tex]
Thus, the composition of the three functions above is
[tex]p(q(r(x)))=p(q(x^2))=p(x^2+3)=\sqrt{x^2+3}=f(x)[/tex]
Hence, the answers are
[tex]\begin{gathered} r(x)=x^2 \\ q(x)=x+3 \\ p(x)=\sqrt{x} \end{gathered}[/tex]
