#### Answer

$f(x)=\sqrt x$ and $g(x)=x^2+1$

#### Work Step by Step

We wish to find two functions $f$ and $g$ such that:
$H(x)=(f \circ g)(x) =\sqrt {x^2+1} $
Let us consider
$f(x)=\sqrt x$ and $g(x)=x^2+1$
Then we have the composite function:
$H(x)=(f \circ g)(x) =f[g(x)]=f(x^2+1)=\sqrt {x^2+1} $