Originally Posted by

**harpazo** In other countries, normal household voltage is 220 volts. It is acceptable for the actual voltage x to differ from normal by at most 8 volts. A formula that describes this is |x - 220| ≤ 8.

A. Show that a voltage of 214 is acceptable.

B. Show that a voltage of 209 is not acceptable.

Question: Must I replace x with 214 and then 209 respectively for parts A and B? /QUOTE]

To say at most means $|V-220|\le 8$.

OR $-8 \le V-220 \le 8 $, that is the same as $212\le V\le 228$.

Now look closely at tat last sequence of inequalities:

$V=214$ works, while $V=209$ does not work!