Question 764988
"F(x) =x^2+2x+4 ; g(x)=v(9-x)      (When I do v() that is a square root symbol)"

You mean this for the second function:  g(x)=sqrt(9-x) or {{{g(x)=sqrt(9-x)}}}


You ask for help with the composition F of g, evaluated at x=-7.
First, form the composition:
{{{F(g(x))=(g(x))^2+2(g(x))+4=(sqrt(9-x))^2+2(sqrt(9-x))+4}}}
{{{9-x+2*sqrt(9-x)+4}}}
{{{-x+2*sqrt(9-x)+13}}}
{{{highlight(F(g(x))=-x+2*sqrt(9-x)+13)}}}


Now just let x=-7 and see what is the evaluation.
{{{-(-7)+2*sqrt(16)+13=7+13+2*4=highlight(28)}}}