Answer:
x = -7
Step-by-step explanation:
[tex]\begin{aligned}f \circ g=f[g(x)] & = \sqrt{9(x+7)}\\& = \sqrt{9}\sqrt{x+7}\\ & = 3\sqrt{x+7}\end{aligned}[/tex]
Domain = input values (x-values)
As we cannot square root a negative number, the domain is:
x ≥ -7 → [-7, ∞)
Therefore, the smallest number that is in the domain of [tex]f \circ g[/tex] is -7
