SOLUTION:

Question 130935:
Answer by SHUgrad05(58) (Show Source): You can put this solution on YOUR website!
Solve.
sqrt( 9x + 81 ) = x + 5
The solution is x = ___7, x=8______
HERE'S HOW:
square both sides of the equation to get - 9x+81=x^2+10x+25
Next simplify: x^2-x-56=0
Next factor: (x-8)(x-7)=0
x=8, x=7