[tex]\sqrt{x+4}-1=8\\\\\text{Domain:}\ x+4\geq0\to x\geq-4\\\\\sqrt{x+4}-1=8\qquad\text{add 1 to both sides}\\\\\sqrt{x+4}=9\qquad\text{square both sides}\\\\\left(\sqrt{x+4}\right)^2=9^2\\\\x+4=81\qquad\text{subtract 4 from both sides}\\\\x=77\in D[/tex]
