[tex]g(x) = \sqrt{x - 4}[/tex]
[tex]h(x) = 2x - 8[/tex]
g x h = [tex]\sqrt{x-4}.(2x-8)[/tex]
Looking at the equation we know that there's no way to have a negative root, so we need x - 4 to be greater than or equal to 0
[tex] x - 4 \geq 0[/tex]
[tex]x \geq 4[/tex]
