For f left parenthesis x right parenthesis equals StartRoot x EndRootf(x)=x and g left parenthesis x right parenthesis equals x plus 7 commag(x)=x+7, find the following functions.
a. left parenthesis f circle g right parenthesis left parenthesis x right parenthesis(f◦g)(x)​;
b. left parenthesis g circle f right parenthesis left parenthesis x right parenthesis(g◦f)(x)​;
c. left parenthesis f circle g right parenthesis left parenthesis 2 right parenthesis(f◦g)(2)​;
d. left parenthesis g circle f right parenthesis left parenthesis 2 right parenthesis(g◦f)(2)​;