Double Five or Five-Six

xxxx x xxxx xxx-xxxxx xxx xxxxxxxxxx, xxxx xxxxxxxxxxx xxxxx. xxx xxxxxxx \(xx\) xxxxx xxx xxxxxxxxxxx xxxxx, xxx \(xx\) xxxxx x xxxx xxxxxxxxxxx xxxxxxxx xx x xxx. xxxxx xxxxxxx xx xxxx xxxxxx xx xxxxxx xxxxx? xxx \(x_{xx}\) xxx \(x_{xx}\) xx xxx xxxxxxx xx xxxxx xxxxx xxxx xxxxxxx xxxxx xxxxxxx, xxxxxxxx xxxx xxx xxxxx. xxxxxx xxxxxxxxxxx, xxxxx x xxx-xxxxx xxxxxx—x xxx xxx xx xxx—xxx \(\xxxxxx{x}[x_{xx}]-\xxxxxx{x}[x_{xx}]\), xxxxxxxx xx xxxxx; xxxxx xx xx xxxxxxxxxx xxxxxx. xxxx xxxxxxxxx xxxx xxxxxxxx xxxxxxx xxxxx xxx xxxxx xxxxxxxxxx.