Answer:
x ≤ 3
Step-by-step explanation:
The expression inside the radical ≥ 0, thus
solve
9 - 3x ≥ 0 ( subtract 9 from both sides )
- 3x ≥ - 9
Divide both sides by - 3, reversing the symol as a result of dividing by a negative quantity
x ≤ 3
Any value of x less than or equal to 3 ensures [tex]\sqrt{9-3x}[/tex] is real