## Precalculus: Concepts Through Functions, A Unit Circle Approach to Trigonometry (3rd Edition)

The formula that describes the acceptable voltage is $$|x-220|\leq 8$$ We plug in the given voltage values and if the inequality proves true, then the voltage is acceptable. a. Since $|214-220|=6\le 8$, then the voltage of $214$ Volts is acceptable. a. Since $|209-220|=11\gt 8$, then the voltage of $209$ Volts is not acceptable.