Help with question: suppose that the factor Q and R are different as followers

We are given the following functions:
[tex]\begin{gathered} q(x)=x^2+6 \\ r(x)=\sqrt[]{x+9} \end{gathered}[/tex]We are asked to determine the following composition of functions:
[tex]r\circ q[/tex]This composition is equivalent to the following:
[tex]r\circ q=r(q(x))[/tex]This means that we will substitute the function q(x) for the value of "x" in the function r(x), like this:
[tex]r(q(x))=\sqrt[]{(x^2+6)+9}[/tex]Now, we add like terms:
[tex]r(q(x))=\sqrt[]{x^2+15}[/tex]Now, since we are asked about the composition when x = 7 we will substitute the values of "x = 7" in the resulting function:
[tex]r(q(7))=\sqrt[]{(7)^2+15}[/tex]Now, we solve the operations:
[tex]r(q(7))=8[/tex]Therefore, the value of the composition of function at "x = 7" is 8. We can use the same procedure to determine the composition of q and r.