Chapter 10 - Radical Expressions and Equations - 10-5 Graphing Square Root Functions - Practice and Problem-Solving Exercises - Page 642: 40

The domain of the function is the set of real numbers less than or equal to $4$.

$y=\sqrt 8-2x$ The radicand cannot be negative. $ 8-2x \geq 0$ $ -2x \geq -8$ $x \leq 4$ The domain of the function is the set of real numbers less than or equal to $4$.