g(x) = √x-4
h(x) = 2x-8
g *h is multiplying the two equations.
Solve for X that makes √x-4 defined:
For a square root of an equation to be defined it needs to at least equal 0:
x-4≥0
Add 4 to each side:
x≥4
Now that g(x) is defined we know the domain.
x≥4