F(r)=r^2+5 at r=x+1, r= 3x, and r=1/x

What they are really asking you is for every value r that you are given. Substitute that vale for r in the given function F(r).. Pronounced the Function F of r.

F(r) = r^{2}+5 we know that r = x+1 soo now its called F at (x+1)<----->F(x+1)

F(x+1) = (x+1)^{2 }+ 5

r = 3x --------------->F(3x) = (3x)^{2 }+ 5

r = 1/x -------------->F(1/x) = (1/x)^{2 }+ 5

hope that helps some