## Precalculus (6th Edition) Blitzer

$[-10, +\infty)$
The radicand (expression inside a radical) of a square root cannot be negative as its root is an imaginary number. This means that the radicand, which is $7x-70$, must be greater than or equal to 0. Thus, $7x-10\ge 0 \\7x \ge 0-70 \\7x \ge -70 \\x \ge \frac{-70}{7} \\x \ge -10$ Therefore, the domain of the given function is $[-10, +\infty)$.