What did diocletian do to address some of the problems caused by an expanding empire?
divided the empire into two halves

moved the capital to byzantium

hired mercenary soldiers to protect rome

established the third triumvirate

Divided the empire into two halves

Explanation:

When Diocletian came to power he was tasked to rule an empire that was in decline. In order to save the Empire and make it possible to govern it, he split it in two. He ruled the East part and gave the West part to Maximian, his colleague. This saved at least the Eastern Roman Empire from collapsing since the West Empire fell not so long after the split.

the correct answer is to reduce tax