Chapter 10 - Radical Expressions and Equations - 10-5 Graphing Square Root Functions - Practice and Problem-Solving Exercises - Page 629: 10

$ x \geq 0$

You can not take the square root of a negative number. Therefore, $\frac{x}{3}$ must be greater than or equal to 0. $ \frac{x}{3} \geq 0$ We multiply 3 to both sides $ \frac{x}{3} \times 3 \geq 0 \times 3$ 3 times 0 is 0 $ x \geq 0$