3. For what values of parameters $a$ and $b$ ( $a$ not equal to $b$ ) does the set of values of the function $a(\sqrt{(a-x)(x-b)}-b)$ coincide with its domain? In your answer, list all possible values of the number $b$ in any order, separated by a semicolon.
Answer: $0 ;-1 \mid-1 ; 0$

## Examples of answer notation:

$1 / 4$

0, $25 ; 0,5$