Given : g(x) =
and h(x)=2x-8.
Let us find g*h(x) function now.
g*h(x) = g(x) * h(x) =

Or g*h(x) =(2x-8)
.
He have square root(x-4) in composite function f*h(x).
So, we need to find the domain, we need to check for that values of x's, square root(x-4) would be defined.
Square roots are undefined for negative values.
Therefore, we can setup an inequality for it's domain x-4≥0.
Adding 4 on both sides, we get
x-4+4≥0+4.
x≥4.
Therefore, Domain is all values greater than or equal to 4.
But, restrictions would be all values less than 4 (because less than 4 would give a negative number inside square root).