Part 1
[tex](f\circ g)(x)=f(\sqrt{x})=4\sqrt{x}+1[/tex]
We need to make sure the radical is defined, meaning the radicand has to be non-negative. Thus, the domain is [tex]\boxed{[0, \infty)}[/tex]
Part 2
[tex](g \circ f)(x)=g(4x+1)=\sqrt{4x+1}[/tex]
We need to make sure the radical is defined, meaning the radicand has to be non-negative. Thus,
[tex]4x+1 \geq 0\\\\4x \geq -1\\\\x \geq -\frac{1}{4}[/tex]
Thus, the domain in interval notation is [tex]\boxed{\left[-\frac{1}{4}, \infty)}[/tex]
