For question 21, I tried answering the question and I found the final answer in my textbook but I don't know how they got the -3 and 3.

x+ 3 213 Find the domain of y 4 - Vx2 9 22. Find the range of y = 2 + V9 + x2. Graph the following ne andal y = x +3 not defined when the denominator is O 4 - - x 2 - 9 4- x- 9 = 0 4 = 1 x-9 ( 4 ) = x - 9 16+ 9 = x X = -25 =$5 (-00, -5) UL-5,-3JU [3, 5)0 (5, 00)